Devices and methods for altering eating behavior

ABSTRACT

A device for modifying an eating behavior of a subject is provided. The device includes a device body which is attachable to GI tract tissue of a subject and functions in altering an eating behavior thereof.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to devices and methods which can be usedto alter an eating behavior of a subject.

During the past 20 years, obesity among adults has risen significantlyin the United States. The latest data from the National Center forHealth Statistics show that 30 percent of U.S. adults 20 years of ageand older—over 60 million people—are obese. Obesity requires long-termmanagement; the goal of treatment is weight loss to improve, preventoccurrence of, or eliminate related health problems.

Numerous approaches for the treatment of obesity are known in the art,including drug treatment, surgical procedures and implantable devices.

Drugs for treatment of obesity fall into three general categories,appetite altering drugs such as dexfenfluramine or sibutramine whichsuppresses appetite by altering neurotransmitter release or uptake inthe brain; metabolism-changing drugs such as Orlistat which prevents theaction of lipases (enzymes that break down fat) produced in thepancreas; and drugs that increase energy output (‘thermogenic’ drugs)such as ephedrine and caffeine which stimulate weight loss by reducingappetite and perhaps by stimulating the body to produce more heat.

Although these drugs offer useful therapeutic effects, there remains aneed for more effective obesity treatment drugs. Such a need will fueltremendous commercial opportunity and so in the future drugs whichtarget gastrointestinal or brain receptors for satiety, or block/mimicthe action of satiety altering hormones and substances (such as ghrelin,CCK, PYY, obestatin, leptin, glucagons, neuropeptide Y and the like)might make their way to the market.

Two forms of surgery have been recommended by government consensuspanels that can be performed to treat severe obesity. Both are forpeople with severe cases of obesity, over 100 lbs above ideal bodyweight (e.g., BMI>40 kg/m²), who have not had effective weight loss withdiet, exercise or drugs.

Gastroplasty involves surgically reducing the size of the stomach, thuslimiting food intake. Vertical band gastroplasty (VBG) is successful inmore than 85% of patients, and weight loss is maintained over prolongedtime periods (Barclay Obes Surg. 2004 November-December; 14(10):1415-8).Gastric bypass surgery (e.g. Roux en Y) creates a small stomach pouchand connects this pouch to the second portion of the intestines. Gastricbypass surgery can initially result in substantial weight loss, andapproximately 80 percent of patients remain at least 10 percent belowtheir preoperative body weight for 10 years after surgery. The efficacyof the procedure is probably due to the increased sense of fullness witha reduced gastric volume and the symptoms of “dumping” associated withthe passage of gastric contents into the intestines, which act asdeterrents to eating (Rosenbaum et al. Obesity NEJM Volume 337:396-407Aug. 7, 1997 Number 6). Although gastric bypass surgery is highlyeffective, it carries a risk of morbidly and it is more extensive anddifficult to perform than gastroplasty.

Numerous devices for altering satiety are also known in the art. Somedevices restrict stomach size or food intake via bands [e.g. lap band etal. MJA 2005; 183 (6): 310-314] or space occupying elements [e.g.intra-stomach balloons—Obes Surg. 2005 September; 15(8):1161-4]. Othersalter stomach or pyloric muscle activity via neuronal or muscularimplanted electrodes (Shikora, Journal of gastrointestinal surgeryVolume 8, Issue 4, Pages 408-412; Xu et al. Gastroenterology2005;128:43-50).

Although numerous treatment approaches are available at present, themost effective approach with the best long term effects is restricted tothe treatment of severely obese people and in addition it requirescomplicated surgery which can lead to severe complications or death.

There is thus a widely recognized need for, and it would be highlyadvantageous to have, an eating behavior altering device and methoddevoid of the above limitations.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided adevice for modifying an eating behavior of a subject comprising a devicebody attachable to tissue of a stomach, the device body being capable ofintermittently contacting a wall region of a duodenum and/or the pylorusand/or the antrum when attached to the tissue of the stomach.

According to further features in preferred embodiments of the inventiondescribed below, the device is sized and configured so as to not haveany substantial effect on flow through the antrum and the duodenum.

According to still further features in the described preferredembodiments the tissue of the stomach is a body of the stomach, theantrum or the pylorus.

According to still further features in the described preferredembodiments the device further comprises a tether attached to the devicebody, the tether being attachable to the tissue of the stomach.

According to still further features in the described preferredembodiments the tissue of the stomach is a body of the stomach, theantrum or the pylorus.

According to still further features in the described preferredembodiments an end of the tether is designed for anchoring in or throughthe tissue of the antrum or the pylorus.

According to still further features in the described preferredembodiments the tether is designed for anchoring in or through thetissue of the stomach.

According to still further features in the described preferredembodiments the tether is an elastic tether.

According to still further features in the described preferredembodiments the tether is sized and configured such that the device bodyis capable of moving between the antrum and the duodenum when the tetheris attached to the tissue of the stomach.

According to still further features in the described preferredembodiments the device body is cylindrical, e.g. egg shaped.

According to still further features in the described preferredembodiments the device body includes at least one protrusion and/orconcavity.

According to still further features in the described preferredembodiments the device body is less than 4 cm³ in volume.

According to still further features in the described preferredembodiments a surface area of the device body is less than 15 cm².

According to still further features in the described preferredembodiments the tether is attachable through the tissue via a t-baranchor.

According to still further features in the described preferredembodiments the device further includes a washer element for preventingerosion of the t-bar anchor into the tissue of the stomach.

According to another aspect of the present invention there is provided adevice for modifying an eating behavior of a subject comprising: (a) adevice body; and (b) a tether having a first end attached to the devicebody and a second end being anchorable to tissue in a stomach, thetether being sized and configured such that the device body is capableof contacting tissue of a duodenum when the second end of the tether isanchored to tissue of the stomach.

According to still further features in the described preferredembodiments the device body is sized and configured so as to notsubstantially obstruct food flow through the antrum and the pylorus.

According to still further features in the described preferredembodiments the tether is an inelastic tether.

According to still further features in the described preferredembodiments the tether is an elastic tether.

According to still further features in the described preferredembodiments the tether is sized and configured such that the device bodyis capable of moving between an antrum and the duodenum when the tetheris attached to the tissue of the stomach.

According to still further features in the described preferredembodiments the device body is cylindrical.

According to still further features in the described preferredembodiments the device body includes at least one protrusion and/orconcavity.

According to still further features in the described preferredembodiments the device body is less than 4 cm³ in volume.

According to still further features in the described preferredembodiments a surface area of the device body is less than 15 cm².

According to still further features in the described preferredembodiments the second end is anchorable to the tissue of the stomachvia in or through tissue anchoring.

According to still further features in the described preferredembodiments the tissue of the stomach is a body of the stomach, anantrum or a pylorus.

According to yet another aspect of the present invention there isprovided an implantable device comprising a device body attached to atleast one tissue anchor, the tissue anchor comprising a tissue anchoringelement attached to a tether having elastic properties.

According to still another aspect of the present invention there isprovided a device for modifying an eating behavior of a subjectcomprising a device body attachable to a tissue of a GI tract, thedevice body being capable of intermittently contacting a wall region ofa duodenum, a pylorus and/or an antrum when attached to the tissue ofthe GI tract.

According to still further features in the described preferredembodiments the device body is attached to the tissue of the GI tractthrough a tether.

According to still further features in the described preferredembodiments an end of the tether is anchored in or through the tissue ofthe GI tract.

According to still another aspect of the present invention there isprovided a method of inducing early satiety in a subject comprisingattaching a device to a tissue of the antrum or pylorus of a subject inneed, the device being configured so as to intermittently contact a wallregion of a duodenum and/or the pylorus and/or the antrum.

According to still another aspect of the present invention there isprovided a system for modifying an eating behavior of a subjectcomprising: (a) a delivery apparatus being capable of anchoring a tetherin or through GI tract tissue; and (b) a device including a device bodyattached to the tether, the device being capable of altering the eatingbehavior of the subject when anchored to the GI tract tissue.

According to still further features in the described preferredembodiments the apparatus includes a vacuum chamber for suctioning avolume of the GI tract tissue.

According to still further features in the described preferredembodiments the apparatus further includes a tissue piercing elementcapable of piercing in or through the volume of the GI tract tissue.

The present invention successfully addresses the shortcomings of thepresently known configurations by providing devices and methods whichcan be used to effectively alter an eating behavior of a subject using asafe, minimally invasive procedure.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. In case of conflict, the patentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

In the drawings:

FIG. 1 schematically illustrates the stomach-duodenum junction showingthe pyloric antrum (PA), the pyloric canal (PC), the duodenum (D), thepyloric sphincter (PS), the submucosal (SM), mucosal (MC), muscle (mu)and serosa (SE) layers and the Pyloric opening (PO).

FIGS. 2 a-c are prior art diagrams illustrating gastric emptying eventsas manifested in the antral/pyloric/duodenal regions of the GI tract.

FIGS. 2 d-f illustrate the effect of the device of the present inventionon the three stages of gastric emptying illustrated in FIGS. 2 a-c.

FIGS. 3 a-c illustrate embodiments of the device of the presentinvention.

FIG. 3 d illustrates an embodiment of the present invention whichutilizes two implanted devices, one having a device body residing in theantrum and another in the duodenum.

FIGS. 4 a-d illustrate several embodiments of the device body of thedevice of the present invention.

FIGS. 5 a-n illustrates additional embodiments of a device constructedin accordance with the teachings of the present invention.

FIGS. 6 a-g illustrates additional embodiments of a pyloric device inthe duodenal/pyloric/antral regions of the GI tract.

FIGS. 7 a-8 c illustrate the positioning and anchoring of one embodimentof the device of the present invention within the pyloric canal andother tissue of the GI system.

FIG. 9 illustrates the use of the anchoring technique of FIG. 8 a-c toanchor a generic sensor or actuator in the stomach wall.

FIGS. 10 a-d illustrate several embodiments of the present device.Implanted devices were retrieved from pigs and photographed over anillustration of GI anatomy to show relative positioning of the devicewith respect to the stomach and duodenum.

FIGS. 11-12 graphically illustrate the daily weight (in kilos) of thethree pigs implanted with the present device as more fully described inthe examples section.

FIG. 13 schematically illustrates one embodiment of the present deviceas anchored in-tissue and provided with a tether-mounted stopper forpreventing unwanted movement of the tether through the tissue.

FIGS. 14-15 illustrate a system used for anchoring the satiety-inducingdevice of the present invention.

FIGS. 16-19 b illustrate anchoring of the device of the presentinvention in the stomach of pigs.

FIGS. 20 a-h illustrate histology of the tissue region used foranchoring showing the benign nature of the anchor described in thisinvention after 6 weeks device implantation in the stomach of a pig.Note the lack of erosion and lack of severe inflammation or tissueremodeling. FIGS. 20 a-b, bar=1 mm; FIGS. 20 c-h, bar=250 μm; sectionwere stained with Haematoxylin & Eosin (HE). FIG. 20 a: Very low powerview of the specimen. The mucosa is towards the top. Arrows point to thetract traversing the sample. An asterisk indicates the space where oneof the bars of the T-shaped implant was located. FIG. 20 b: Low powerview of the specimen. The tract is in the center. Squares indicate theregions from which higher power views were obtained. The letter in eachsquare refers to the relevant image. FIG. 20 c: Medium power view of thetract within the submucosa. An asterisk indicates the lumen of thetract. This is where the implant was located. The lumen/implant issurrounded by loose fibrous tissue and inflammatory cells. (The latterare difficult to resolve at this magnification). FIG. 20 d: Medium powerview of the tract within the tunica muscularis. An asterisk indicatesthe lumen of the tract. In this area a small amount of fibrin adheres tothe wall of the tract (small arrows) and the inflammatory infiltrationis more intense—seen as the granular blue staining in the center. FIG.20 e: High power view of the wall of the tract (the lumen is indicatedwith an asterisk). There is lymphohistiocytic infiltration and fibrosis,typical of reaction to a foreign body. FIG. 20 f: High power view of thetunica muscularis showing multifocal predominantly perivascularmononuclear infiltration and vacuolation in the smooth muscle cells.FIG. 20 g: Medium power view of the mucosa in the immediate vicinity ofthe tract. There is mild distortion of crypt architecture with localizedhyperplasia and mucous metaplasia. FIG. 20 h: High power view of part ofthe field shown in FIG. 20 g. Away from the small area with mucosalhyperplasia and mucous metaplasia (the left half of the image), themucosa is essentially unremarkable and contains the normal complement ofparietal cells. A black line indicates the interface between these tworegions.

FIGS. 21 a-c illustrate an apparatus for delivering and positioning adevice constructed in accordance with the teachings of the presentinvention.

FIGS. 22 a-b illustrate the delivery apparatus utilized for anchoring agastric device in the pyloric sphincter of pigs (FIG. 22 a) and theanchored device following the procedure (FIG. 22 b).

FIGS. 23 a-c schematically illustrate operation of a preferredconfiguration of a delivery device constructed in accordance with theteachings of the present invention.

FIG. 24 schematically illustrates a preferred configuration of a vacuumcup for efficient through-anchoring and placement of an anchor outsidethe wall of a lumen (e.g. stomach).

FIGS. 25 a-c schematically illustrate in-tissue anchoring of the presentdevice using a coil anchor.

FIG. 26 illustrates anchoring of the device of the present invention inthe stomach of a live pig as is described in detail in Example 7.

FIG. 27 illustrates pig stomach tissue recovered along with anchoreddevice, showing that anchoring the device of the present invention usingthe present approach does not result in any tissue erosion orinflammation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of devices and methods which can be used toalter an eating behavior of a subject.

The principles and operation of the present invention may be betterunderstood with reference to the drawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details set forth in the following description or exemplified bythe Examples. The invention is capable of other embodiments or of beingpracticed or carried out in various ways. Also, it is to be understoodthat the phraseology and terminology employed herein is for the purposeof description and should not be regarded as limiting.

The pylorus is the region of the stomach that connects to the duodenum(FIG. 1). It is divided into two parts: the distal antrum (DA) orequivalently the pyloric antrum (PA, FIG. 1), which connects to the bodyof the stomach, and the pyloric canal (PC, FIG. 1), which connects tothe duodenum (D, FIG. 1). The pyloric sphincter (PS, FIG. 1), or valve,is a ring of smooth muscle (mu, FIG. 1) at the end of the pyloric canalwhich is surrounded by the submucosal (SM, FIG. 1) and mucosal (MC,FIG. 1) layers of the GI tract. The pyloric sphincter is part of asystem responsible for controlling the flow of food from the stomach tothe duodenum. The pyloric opening (PO, FIG. 1) is the opening surroundedby the lips of the pyloric sphincter (PS) and under certaincircumstances also includes part of the pyloric canal (PC). Its diametervaries depending mainly on the degree of contraction and relaxation ofthe pyloric canal and sphincter. Studies have shown that when fullyopen, the diameter of the opening can vary between 5-25 mm.

The stomach plays an important role in the digestion of food bychemically/enzymatically breaking down food particles via secretedgastric acid and pepsin and by mechanically breaking down food particlesvia peristaltic contractions.

In normal digestion, as the stomach fills, digestive glands in thecorpus and fundus release hydrochloric acid, a strong acid that helpsdigest food and facilitate the conversion of digestive enzymes intotheir active form. The peristaltic contractions of muscles within thestomach wall, especially in the antral region, mix digestive juices andfood to produce a semi-fluid substance known as chyme. Chyme ismobilized into the duodenum through a coordinated antral-pylorus actionwhich is triggered by the consistency of the chyme.

The antrum plays a central role in grinding the food particles intochyme. A representative sequence of gastric emptying events asmanifested in the antral/pyloric/duodenal regions is illustrated byFIGS. 2 a-c. Although this is believed to be an accurate depiction ofgastric emptying in humans, it should be noted that the present deviceis not bound in function to the specific gastric emptying sequenceillustrated by FIGS. 2 a-c and thus will also function in the mannerprescribed herein during a different gastric emptying sequence.

FIG. 2 a-c illustrates the three stages of gastric emptying in theantral/pyloric/duodenal regions. Although these stages occur in onesmooth integrated movement, the process is divided into distinct stagesfor illustrative purposes only. The timing of the closing of thedistinct parts of the pyloric cylinder are crucial in determiningwhether food is evacuated into the duodenum or retropropulsed back intothe stomach while simultaneously being ground by the antral mucosalfolds. During contraction of the pylorus P (FIG. 2 a) there may be aninterplay between its right pyloric loop muscles (surrounding thepylorus P) and its left muscle loop (forming the antral contraction waveACW) in the region of the sulcus intermedius. Should the pylorus (P)close first, retropropulsion and grinding of contents back into theantrum may occur; should the antral contraction wave (ACW) contractfirst, propulsion and evacuation into the duodenum may occur. In theearly phases of digestion (shown in FIG. 2 a), an antral contractionwave ACW forces food into the distal stomach against a closed or closingpylorus. In FIG. 2 b, the antral contraction wave (ACW) reaches aminimum diameter two to three centimeters proximal to the pylorus (P) atwhich point the mucosal folds of the antrum touch and grind the foodwith a bolus of chyme trapped between this point and the closed pylorus(P) in a space called the pseudodiverticulum (PD) in a process calledgrinding and retropropulsion (see Keet et al., The Pyloric SphincterCylinder in Health and Disease, online edition). The contents of thepseudodiverticulum (PD) are not intended to be transferred into theduodenum at this stage. At a later phase of digestion (termedevacuation, shown in FIG. 2 c), when the pylorus is patent and does notrestrict flow, the antrum contraction wave (ACW), differences in staticpressure between the antrum (A) and the duodenum (D), and/or theformation of a pyloric canal (PC in FIG. 2 c indicates the musclesforming the pyloric canal) evacuates the contents of thepseudodiverticulum (PD) into the duodenum (D) (see Keet et al., ThePyloric Sphincter Cylinder in Health and Disease, online edition).

Physiological reflexes in the form of electrical, hormonal, chemical ormuscular signals are initiated from the duodenum in response to thepresence of an excess or change in the composition or characteristics ofchyme. Such signals are relayed back to other regions of the GI tract(e.g. pylorus and antrum) to slow or even stop food churning and/orstomach emptying; in addition, satiety-inducing (hormonal or electrical)signals are relayed to the brain (Guyton and Hall Textbook of MedicalPhysiology, pages 785-6; 2006).

Thus, the antro-duodenal region of the stomach plays an important rolein digestion and feedback.

While reducing the present invention to practice, the present inventorshave uncovered that anchoring of a device within the stomach in a mannerenabling contact between the device body and the wall of the antrum,pylorus or duodenum leads to a reduction in eating rates and weight gainin a large mammal. As is illustrated in the Examples section,implantation of one embodiment of the present device in pigs led tomarked decrease in weight gain (see FIGS. 11-12 for a graphical summaryof the results).

Thus, according to one aspect of the present invention there is provideda device for modifying an eating behavior of a subject. As used herein,the term subject denotes an animal, preferably a mammal such as a human,e.g. a human having an eating disorder or a weight related disorder.

A presently preferred embodiment of the present device includes a devicebody which is directly or indirectly attachable to tissue of an antrumor a pylorus in a way which enables the device body to intermittentlycontact an adjacent or opposite wall region of an antral-duodenal regionwhen attached to said tissue of the antrum or the pylorus. As usedherein, the phrase “antral-duodenal region” denotes any mucosal tissueresiding within a region of the gastrointestinal (GI) tract starting atthe proximal antrum and terminating at the distal duodenum.

It will be appreciated that although antrum or pyloric anchoring ispresently preferred, other GI tract anchoring sites (e.g. body of thestomach, fundus, lower esophageal sphincter etc) are also envisaged.

Preferably, this embodiment of the device of the present invention isconfigured so as to intermittently contact mucosal tissue residingwithin the antrum, pylorus and proximal region of the duodenum (duodenalbulb), as well as the duodenal side of the pylorus.

FIGS. 3 a-c illustrate several configurations of this embodiment of thepresent device which is referred to herein as device 10.

Device 10 includes a device body 12 and a tether 14. When device 10 isin use, an end 16 of tether 14 is attached to tissue of the antrum. Suchattachment can be facilitated via a loop of the tether material itself,a t-bar anchor, coil, suture thread, staples, clips and the like.Preferably, an end 16 of tether 14 is inserted into the antrum tissue(through the mucosa, submucosa and optionally muscle and serosa) andeither affixed to itself in a loop with a knot or other swaging device,or secured via a tissue anchor.

Tissue anchoring is classified herein as through-tissue or in-tissueanchoring. In-tissue anchoring implies that the anchor and part of thetether rests within the tissue (e.g. anchored with an in-tissue coil orbarb). In-tissue anchoring is exemplified by FIGS. 25 a-c.Through-tissue anchoring involves having the anchor reside outside thelumen or with the anchor residing inside the lumen and only part of thetether residing in the tissue itself. Through-tissue anchoring isexemplified by FIGS. 13 and 23 a-c. Through-tissue anchoring can beeffected with a needle using direct visual guidance through the workingchannel of an endoscope (see FIGS. 16-18). Alternatively, a vacuum cupcan assist in through-tissue anchoring. With reference to FIG. 24,apparatus 200, which includes a vacuum chamber which is symmetricallyarranged around a delivery needle 206 can be used to effect the in-outanchoring scheme. Centering needle 206 in vacuum chamber 202 (cup)ensures the needle 206 follows the shortest path through tissue 82. Inthis manner, it is not necessary to approach tissue 82 at a normal anglewhich is difficult to do using an endoscope at any given position in theGI tract. Rather, the endoscope tip is positioned roughly normal andvacuum chamber 202 forces tissue 82 to be flat against the bottom of thecup and normal to the axis needle 206 penetration. If needle 206 is notcentered in the vacuum chamber 202, needle 206 could go into the wall oftissue 82, but not penetrate to the other side as tissue 82 around thecircumference of vacuum chamber 202 is not normal to axis of needle 206.

Suitable tissue anchors for both in-tissue and through-tissue anchoringcan include t-bar or mushroom-like elements which can be buried withinthe tissue or juxtaposed against the tissue at the exit site. Methods ofinserting such anchors include open surgery, laparoscopic or endoscopicmeans known in the art and developed for such procedures, e.g. naturalorifice transgastric endoscopic surgery (NOTES). Additional approachesfor anchoring the present device are described in Example 5.

In any case, and with further reference to FIG. 3 a-d, tether 14 isattached to the tissue of the antrum in a way which ensures a secureconnection which can withstand the forces acting on device body 12 andtether 14 during GI tract movements. Tether 14 or anchor 16 can bedesigned to degrade and detach after a set time in the acidic or bileenvironment of the stomach or duodenum respectively. In this manner,device 10 can be designed to remove itself after a set time and device10, or components thereof, can pass through the GI tract and be removedfrom the body.

Device body 12 can be fabricated from a wide range of biocompatiblematerials. Examples of suitable material include polymers such aspolyurethane and polypropylene, silicone, latex, Teflon™, ceramics,NITINOL, passive metals, alloys and the like.

Additional coatings for preventing biofilm formation, encapsulation,erosion and antigenic reactions can also be employed. The prior art isreplete with examples of materials that can be used for such purposes[see for example, Baveja et al. Biomaterials. 2004 September;25(20):5003-12] or Surfacine™ (www.surfacine.com).

Coatings including medicaments or pharmaceutically active agents arealso contemplated herein, examples of active agents include, but are notlimited to hormones such as CCK, ghrelin, motilin and the like.Alternatively, coatings which stimulate chemoreceptors (e.g. fat orfat-like substances, sugars and the like) can also be utilized.Non-releasable coatings (e.g. attached through non-degradable linkers)are preferred for prolonged effect.

Furthermore, the device of the present invention can be anendoscopically-refillable reservoir for medicaments, pharmaceuticallyactive agents such as hormones small molecules or other peptides, aswell as chemical agents such as, by way of example, hydrochloric acid,which is known to suppress motility when in contact with the duodenalmucosal surfaces.

Again with reference to FIGS. 3 a-d, device body 12 is preferably sizedand configured so as to minimize any direct effect on antro-pyloro andantro-duodenal flow of chyme. Preferably, device body 12 is sized andconfigured so as to not have any substantial direct effect on such flow.Furthermore, device body 12 is selected of a length and diameter so thatit can pass safely through the duodenum if it becomes detached fromtether 14 or the anchoring tissue, thereby minimizing the risk of ablockage of the small intestines.

Thus, a volume of device body 12 is typically selected from a range of0.03-12 cm³. Such volume can be distributed over a cylindrical shape,having a length of 1-4 cm and a diameter of 0.1-2 cm. Other shapescontemplated herein include spheres, ellipses (e.g. egg ortorpedo-shaped), discs, cubes, triangles, protruding fingers, amorphousshapes and the like. The surface of device body 12 is preferably smoothso as to minimize any shear forces applied to mucosal tissue of theantrum, pylorus and/or duodenum and to minimize the chance of bezoarformation around device body 12, but also potentially ridged to betterstimulate the tissue. The surface of device body 12 can be porous,pitted or shaped in the form of one or more cups to retain a bit ofchyme on the device surface via capillary forces and therefore prolongthe stimulation of the chemical sensors in the duodenum that sense thepresence of chyme, hence slowing gastric motility.

Device body 12 can be fabricated using any one of several well knownfabrication techniques including, but not limited to, casting,extrusion, machining and the like.

A device body 12 fabricated from silicone having a Shore A hardnessrange of 5-100 is presently preferred for its biocompatibility,durability and low surface hardness. It is preferable that all parts ofthe device that are in contact with the submucosa of the GI tract aresoft enough to bend, deform and extend elastically to a degreesufficient to not cause erosion of the mucosal surfaces despite thepressure and motion exerted on the device by the GI tract.

Device body 12 can be attached directly to the GI tissue with anchor 16if excessive movement relative to the anchoring point is not desired.Alternatively, the length and composition of tether 14 is selectedaccording to the intended function of device 10. The length of tether 14can be anywhere from 0.5 cm to 10 cm and largely depends on the site ofattachment of end 16 and function of device 10. Tether 14 can be rigidor elastic; a rigid tether 14 can be fabricated from a polymer (e.g.polyethylene, PTFE, or nylon); while an elastic tether 14 can befabricated from silicone, polyurethane, latex, and the like. The elastictether can have an elastic configuration and yet be made from anon-elastic material, e.g. a coil made from a polymer, or it can befabricated from an elastic material such as silicon. A tether having afirst portion which is elastic and a second portion which is not elasticcan also be utilized by the present invention.

In a preferred embodiment, tether 14 is made of a highly elasticmaterial such as silicone and will extend like a rubber band, therebyminimizing the forces acting to rip device 10 out of its anchoredposition. Typical diameter of tether 14 can be anywhere from 0.1 mm to 1cm.

As is mentioned herein, device 10 of the present invention is configuredso as to enable intermittent contact between device body 12 and walltissue of an antral-duodenal region. Such functionality can be achievedvia one of three general configurations of device 10.

FIG. 3 a illustrates a configuration which enables device body 12 tomove within or shuttle between the antrum and duodenum and thusintermittently contact a wall tissue of the duodenum, pylorus and/orantrum.

Tether 14 length and device body 12 size are preferably selected suchthat when device body 12 resides within the duodenum, it does not gomore distal than the first 10 cm, preferably, first 5 cm of theduodenum.

Tether 14 and device body 12 of this configuration of device 10 ispreferably fabricated from silicone. Tether 14 length can be anywherefrom 0.5 cm to 10 cm, while device body 12 can be shaped as a cylinderor torpedo having a volume of about 4 cm³ or less and/or with surfacearea of 15 cm² or less. Attachment of device body 12 to tether 14 can beeffected via gluing, pinning and the like. Alternatively, device body 12and tether 14 can be cast as a single part and be of unitaryconstruction.

Due to the length of tether 14 and the shape and size of device body 12,this configuration of device 10 will shuttle or move within or betweenthe antrum and duodenum through the pylorus due to natural peristalticand reflux forces present in the GI tract and thus intermittentlycontact mucosal tissue of the duodenum, pylorus and antrum.

Such intermittent contacting will be largely influenced by movements ofthe GI tract (e.g. peristaltic movement of the antrum and duodenum aswell as sphincter movement of the pylorus) as well as flow of chyme fromthe antrum to the stomach body (retropropulsion) or from the antrum tothe duodenum and bile reflux from the duodenum to the antrum. Flow ofchyme from the antrum to the duodenum, will carry device body 12 intothe duodenum (as shown by I), while retrograde flow of bile from theduodenum into the antrum may carry device body 12 into the antrum (shownby II). Such shuttling back and forth can occur 2 to 3 times per minutewhen the subject is feeding. Without being bound to a theory, thepresent inventors are of the opinion that such shuttling will activatereceptors present in the duodenum and antrum and thus reduce eating rateand/or eating amount.

FIG. 3 b illustrates a configuration of device 10 in which device body12 resides in the duodenum intermittently contacting mucosal tissue ofthe duodenum and pylorus and does not shuttle into the antrum. In thisconfiguration of device 10, tether 14 is attached to pylorus,antro-pylorus or duodeno-pylorus tissue (mucosa, submucosa andoptionally muscle) and is long enough to allow device body tointermittently contact the wall of the duodenum and the pylorus (at theduodenal side). Device body 12 can be shrunk to dimensions of tether 14and therefore contact of the GI tissue with tether 14 alone (or tethersif multiple devices are present) will be sufficient to create thedesired change in the eating behavior of the subject.

It will be appreciated that device 10 configuration also enablesapplication of back pressure on the pylorus wall (at the duodenal side)especially when bile flows from the duodenum to the antrum. The duodenumdoes not normally contain food particles, and therefore any suchpressure or mechanical stimulation of a solid substance may generate asignal that solid food has managed to get into the duodenum, and that inturn may drive signaling to slow down gastric motility in general.

FIG. 3 c illustrates a configuration of device 10 in which device body12 resides in the antrum intermittently contacting mucosal tissue of theantrum and possibly the pylorus and does not shuttle into the duodenum.

In this configuration, tether 14 is attached to tissue of the antrum andis long enough such that device body can contact the walls of theantrum, as well as walls of the pylorus (at the antrum side andoptionally the opening).

Device 10 of the present invention provides several advantages overprior art devices which reside in the antrum and/or duodenum.

Most antrum/duodenum devices, such as, for example, the antrum-anchoredballoon described in U.S. patent Ser. No. 10/872,910, the artificialbezoar described in U.S. Pat. No. 7,066,945 or the flow reductiondevices described in U.S. patent application Ser. No. 11/300,283function by directly reducing the flow through the antrum, pylorusand/or the duodenum or by occupying a space within these regions therebyeffectively reducing the volume thereof.

In sharp contrast, device 10 of the present invention is designed forleveraging innate mechanical, neurological and biochemical feedbackmechanisms that control GI motility and that arise from the stimulationof the lumen of the GI tract and interference with the normalperistaltic sensations of the lumen.

It will be appreciated that the present invention can also utilizeconfigurations which include several implanted devices.

FIG. 3 d provides one example of such a multi-device 10 configuration.In this example, two devices are utilized each being separatelypositioned in a specific location of the antro-duodenal region. A firstdevice 10 is positioned so as to reside in the duodenum and a second inthe antrum. Such a configuration (which can also be realized using asingle tether-attachment location) effectively stimulates both regionssimultaneously.

Another example of a multi-device configuration includes 2-5 device 10configurations each including device body 12 shaped as a hollow or solidsphere having a volume of about 1 cm³. Each of the devices can beindividually tethered to one or more tissue locations in the antrum orduodenum. The surface of such a sphere can smooth or provided withprojections. In this embodiment, the effective volume and surface areaof the combined devices is increased linearly with the number of devicesimplanted, which increases their stimulation capability, while the sizeof each individual device 10 is kept to a minimum to enable easyintroduction into the stomach, easy anchoring, minimize the forces oneach device 10, and ensure that each device 10 is small enough to safelypass through the small intestine if it becomes detached from the tissueto which it is anchored.

It will be appreciated that although the device configurations describedabove include a tether 14, it should be noted that direct attachment ofdevice body 12 to the tissue, at least in the case of the deviceillustrated in FIGS. 3 c-d is also contemplated herein. Such directattachment can be realized using clips, staples, barbs, sutures and thelike.

Since it is possible that device body 12 functions in stimulatingmechano-receptors present in the walls of the duodenum antrum andpylorus, the present inventors have also devised device body 12configurations which maximizes surface contact and stimulation ofmechano-receptor and while minimizing flow obstruction.

FIGS. 4 a-d provide several examples of such device body 12configurations, including a device body 12 which incorporates whiskers(FIG. 4 a), soft projections (FIG. 4 b), flat discs for applying backpressure on the duodenal side of the pylorus (FIG. 4 c) and spaghetti-or ribbon-like extensions (FIG. 4 d). The example configuration depictedin 4 c can also serve as a one way flap valve to prevent reflux of GIcontents from one side of a sphincter to the other, and if so engineeredto resist flow in the forward direction as well. Device body 12 can alsoincorporate at least one concavity which can act as a surface reservoir.

Device 10 can also incorporate several other mechanisms for enhancingits effect in inducing early satiety.

For example, device 10 can include electrodes positionable on devicebody 12 and powered by a power source positioned at the site of tether14 attachment. Such a power source can be a battery, or a self containedpower generating device (further described hereinunder). Tether 14 caninclude insulated wires for carrying the current produced by the powersource to the electrodes positioned on the surface of device body 12.Since device body only intermittently contact tissue, an electriccurrent will be periodically applied to the tissue.

The power source can also be configured such that the acid in thestomach is used to generate electricity. In this embodiment, pieces ofmetal, for example zinc and copper are electrically isolated from oneanother in the antrum but both exposed to stomach acid. The electriccurrent is generated by the chemical reaction between the acid in thestomach and the zinc. The reaction occurs according to the following:

At the anode, zinc is oxidized:

Zn→Zn2++2 e−

At the cathode, hydrogen is reduced:

2H++2e−→H2

The insulated wires connected to the pieces of zinc and copper run thelength of the tether and end in one of more bipolar electrodes thatelectrically stimulate the duodenal tissue as device body 12, orprotrusions thereupon randomly contact the duodenum tissue duringperistalsis and passage of chyme.

The electricity generating power source described above can stimulatethe pylorus or antrum in addition or instead of electrical stimulationof the duodenum. In the antrum-only example, the stimulating electrodescan be a part of the anchoring mechanism, or as separate flexibleprotrusions that are free to move around and contact the mucosalsurfaces of the antrum randomly, thereby providing a combined electricaland mechanical stimulation of the antral tissue.

Electrical stimulation of the GI tract tissue can also be effected usingelectrodes embedded in the mucosal, submucosal or muscle layers of thestomach using endoscopically-introduced electrode anchors or screws andthereby be used to alter (enhance in the case of gastroparesis or delayin the case of obesity) gastric motility using electrode positions andstimulation parameters known in the art. Many external gastricstimulators are known in the art. The device described herein can beintroduced and implanted using an endoscope, which is significantly moretolerable than an open or laparoscopic surgical procedure used inexisting gastric electrical stimulators.

The device described above can run open loop, i.e. only turns on when asubject is eating and gastric acid is being generated. Furthermore, thedevice requires no external power source with the requisite change orrecharging of batteries. Alternatively, the device can have an on boardbattery or capacitor to store excess energy for future use, onboardelectronics to regulate and condition the stimulation parameters,interface with sensors that detect parameters such as the current pH,presence and composition of food, as well as wireless communicationcapabilities to allow for control of the device from outside the body.

At some point, the zinc will be fully degraded and the device can berecharged with new zinc, or the entire device can be replaced. Forexample, the metals can be replenished orally using the magneticretention mechanism describe elsewhere in this patent applicationMaterial substitutions are possible. Carbon can be used instead ofcopper for example. Other metals can be also be used. For example, usinga piece of magnesium instead of zinc approximately doubles the currentproduced by the device (approx. 240 μA with zinc to about 400 μA withmagnesium in 5% citric acid) and increases the voltage (0.97 V with zincto 1.6 V with magnesium in 5% citric acid). Even higher voltages andcurrents are anticipated in the hydrochloric acid environment of thestomach with a concentrated pH of 0.8 and a diluted pH of 2-3. Two ormore such devices can be wired in series to increase the voltage or inparallel to increase the current they supply to whatever level needed toprovide effective stimulation.

Studies have shown that the presence of acid in the duodenum can triggersatiety feedback signals and/or slow gastric emptying and motility.Thus, device 10 can also include a mechanism for carrying gastric acidfrom the antrum to the duodenum, thereby bypassing the pyloric valve.Such a mechanism can include a collector positioned at the site oftether 14 attachment. Such a collector can be a gel or porous polymer(such as porous PTFE or polypropylene) which imbibes the gastric acidwithout getting clogged by food particles or chyme. Tether 14 caninclude a conduit for relaying collected gastric acid through thepylorus to the surface of device body 12 present in the duodenum.Contact of device body 12 with duodenal tissue can release the acid, oralternatively contractions and increased pressure within the antrum cancreate a pressure difference to delivery the acid through the conduit.In addition to acid, the conduit described above can convey liquidchyme, which can include sugars, fats and other components that cancause a dumping effect which will reduce eating rate and eating amount.In an alternative embodiment, device 10 can contain solid tether 14shaped so that it will not allow the pylorus to seal properly in orderto allow chyme to be transferred prematurely into the duodenum to inducea slight dumping effect.

In a further embodiment, device 10 comprises an anchorable balloon thatresides in antrum and is filled with a gas or liquid. Tether 14 forms aconduit to transfer the fluid or gas to body 12 on device 10 that ispresent in the duodenum. When the antrum contracts the balloon in theantrum, fluid or gas is transferred through the conduit in tether 14 andinflates body 12 which then mechanically stimulates the duodenum,thereby affecting the eating behavior of the subject.

As is mentioned hereinabove, device 10 functions to modify an eatingbehavior of a subject by possibly activating mechano-receptors whichinduce early satiety and/or a slowing of gastric emptying and motility.

Several approaches for implanting device 10 are contemplated herein,including open surgery, laparoscopic surgery and endoscopic surgery.

In the open surgery approach, a physician gains access to theantro-pyloro region through a full incision and anchors/sutures end 16of tether 14 to the antral or pyloric tissue. Following anchoring thephysician places device body 12 within an antral or duodenal region andcloses the stomach and skin incisions.

The laparoscopic approach is largely similar with the only majordifference being replacement of the open incision with three or moresmall incision through which the device can be guided into positionusing laparoscopic equipment.

A combined laparoscopic and endoscopic procedure can be used as well. Alaparoscope can be introduced and positioned so that it impinges on theexternal surface of the stomach where the anchoring is desired. Theimpingement can be viewed from inside the stomach using an endoscope andthe endoscope maneuvered to anchor the device at the point ofimpingement. The laparoscope can then be used to manipulate the anchoron the external surface of the stomach (for example guide it back intothe stomach) or simply to confirm that the anchor site has no long termbleeding or other complications.

Endoscopic placement of device 10 of the present invention can befacilitated using an endoscope-mounted/delivered guide. The endoscopecan be temporarily anchored against the distal end of the pyloricsphincter using an inflatable balloon in order to facilitate placementand anchoring of device 10 using the endoscope-mounted guide.Alternative methods known in the art for determining the position of theguide include direct visual feedback, fluoroscopic guidance, andpotential or pH differences between the pyloric antrum and the duodenum.The guide can be advanced through the working channel of a GI endoscope.

Device 10 can then be advanced to the site of implantation, or it can bepreloaded onto the endoscope end. Alternatively, device 10 can beconfigured for ingestion such that it is temporarily located in thestomach or trapped there by virtue of its size to not pass through thepylorus. Device 10 in such a configuration can be wrapped with anacid-sensitive coating that protects the esophagus of the subjectswallowing the device and then the coating dissolves and device 10unfolds and exposes its anchoring mechanism. Following ingestion, anendoscope mounted guide can be used to capture the device, position andanchor it in the relevant tissue. It will be appreciated that in such adelivery approach, device reconfiguration following capturing ispreferred since once device 10 is attached to the tissue it should becapable of passing through the pylorus (i.e. achieve shuttling if needbe, or be passed down the GI tract and excreted without causing blockagein case tether 14 detaches from the tissue). An example of a deviceconfiguration which can be delivered via ingestion is a multi-deviceconfiguration which includes several devices attached to antrum tissue.In such a scenario, the devices can be ingested as a single unit whichis large enough not to pass through the pylorus. Once trapped in theantrum, a guide can be used to separate and individually position eachof the devices. Following positioning and antral tissue attachment eachdevice is now capable of shuttling through the pylorus (if so desired)or passing through the GI tract if accidentally detached.

Regardless of the approach used for delivering device 10, once device 10is positioned, tether 14 is attached to the mucosa/submucosa andoptionally muscle using sutures, staples, clips or by running end 16 oftether 14 through the tissue and anchoring it within the tissue orproviding or deploying a back stop (e.g. t-bar) at the site end 16 exitsthe tissue. Such attachment can be facilitated by a mechanism disposedon the end of the guide. The mechanism can be an auto-suturing or anauto-stapling mechanism. Following implantation the guide and endoscopeare retracted.

Any of the above surgical approaches can be effected using a twoseparate procedures. In a first procedure, an anchor for tether 14 isestablished, while in the following procedure, device 10 is reversiblyor permanently attached to the anchor point.

The anchor point can be a loop of silicone (configured like an O-ring)which is implanted into an incision made in antrum tissue; the incisionis closed such that a portion of the loop remains exposed in the antrum.Once the tissue heals around the silicone, device 10 is attached ontothe exposed loop portion via a device positioning procedure. Theconfiguration described above can allow for rapid installation, removalor exchange of different sized or configured device bodies based on theneed of the subject, without needing to place additional anchors or makeany further incisions or punctures into the tissue.

The above described devices can be anchored to stomach tissue usingnon-elastic or elastic tethers. Preferably, the device of the presentinvention is anchored to stomach tissue via at least one tetherconfigured for elastic compliance. Human tissues are dynamic and theforces and strains generated by tissue movement can be large enough tocause non-compliant sutures or tethers to cut through or rip out oftissue or erode surfaces such as mucosa. This is especially true if anon-compliant suture or tether attempt to constrain the normal motion ofthe tissue or is in a geometry that does not allow for relative motionbetween itself and the tissue. Therefore, compliant anchoring as taughtby the present invention is preferred as it does not constrain thetissue from its natural movement and thus minimizes the chances ofanchor failure and tissue erosion.

Anchoring of the device body is effected using an elastic tether whichis attached to a tissue anchoring element suitable for providing in orthrough-tissue anchoring capabilities. Examples include t-barstructures, barbs, coils, pig-tail structures (e.g. anchoring elementswhich form coiled pig tail structures when relaxed and linearize whenforcibly pulled), umbrellas, balls (expandable, static, hollow, solid orwire) screws, augers, or any other structures capable of residing in oragainst a tissue and opposing a force applied thereto in one or moredirections, whether designed to be permanent or removable.

The tissue anchoring element can be fabricated from any materialincluding metals, alloys, polymers and the like. The anchoring elementstructure can be rigid, compliant or elastic in nature. The anchoringelement can be constructed from a combination of materials which providethe rigidity necessary for resisting forces applied to the anchor whilemaintaining a soft non-traumatic interface with the tissue, therebyminimizing tissue abrasion. For example, a t-bar anchoring element canbe constructed by overmolding a rigid plastic or metal bar or wire withsilicone to form a T which has a silicone covered cross bar and asilicone tether stem. The use of overmolded metal also provides theanchoring element with radio-opacity and thus enables identificationthereof using imaging techniques. Alternatively part or all of theanchor, tether and body of the device can include a radio-opaquematerial during fabrication, such as barium sulfate.

The loading capabilities of the anchoring element are determined by acombination of structure, size and choice of materials. It will beappreciated that such loading capabilities can be designed into theanchoring element according to use and site of anchoring.

As used herein, the phrases “elastic properties” or “elastic compliance”are used interchangeably to refer to the ability of the tether or aportion thereof to reversibly increase in length under a pulling force.Such an increase in length can be at least 10%, preferably at least 25%,more preferably at least 50%. The elastic properties of the tether canbe provided by the tether structure, cross sectional and axialgeometries and/or tether material.

The tether can be a hollow or solid thread or string-like structurewhich includes one or several adjoined portions. The tether can be madeout of a twisted or braided set of smaller elastic filaments, much likea bungee cord. Such a braided design will allow cell ingrowth and betterintegration into the host tissue, A tether constructed from two adjoinedportions can be used to provide a unique elastic profile, wherein oneportion elastically stretches and another does not, or where bothportion stretch, each to a different degree. A multi-portion tetherconfiguration can also be used to simplify construction of the anchor ofthe present invention. For example, the anchoring element and a firstportion of the tether can be molded from a single material and attachedto a second and elastic portion of the tether via gluing, press fit,over-molding and the like. A multi-portion tether configuration can alsobe used in cases where different portion are exposed to differentenvironments, for example, when a first portion of the tether resideswithin a tissue and another in a lumen. The tether material can beinelastic and yet the tether can be configured to provide elasticity,e.g. an elastic coil structure. For example, the tether can be inelasticand be wound around a rotary-spring-loaded drum in the device body toallow for an elastic effect with inelastic materials.

FIG. 13 illustrates one preferred configuration of the present device asanchored into tissue.

Device 10 includes a device body 12 which is anchored into tissue of theGI tract.

In a preferred configuration of device 10, tether 14 (which in this caseis composed of an elastic portion 17 and an inelastic portion 19) isprovided with an anchoring element 13 which enables, through-tissueanchoring. To enable through-tissue anchoring, anchoring element 13 andattached inelastic portion 19 of tether 14 are delivered from within thestomach through stomach wall tissue or a GI sphincter (as describedhereinbelow) and anchor element 13 is deployed and juxtaposed againstthe outermost tissue layer (serosa) of the stomach, through and againstthe inner luminal surface of an invaginated tissue fold in the lumen ofa GI tract, or against the backside of a sphincter such as the duodenalside of the pyloric sphincter or the stomach side of the loweresophageal sphincter.

Through-tissue anchoring is preferred for its anchoring strength. Whileexperimenting with several tissue anchoring designs, the presentinventors have discovered that devices anchored within stomach tissue(e.g. through stomach wall, a tissue fold or through a sphincter) usingthrough-tissue t-bar anchoring and elastic tethers resulted inconsistent anchoring results while minimizing tissue necrosis and damageat the site of tissue penetration (see FIGS. 20 a-h).

Anchoring through a sphincter or a tissue fold is advantageous in thatthe anchoring element is maintained on the luminal side of the GI tract.This feature ensures that the anchoring element is released into the GItract when disconnected from the tether and can be recovered orharmlessly passed out of the body. Keeping the anchoring element on theluminal side of the GI tract can also be achieved with stomach wallanchoring by simply delivering the anchoring element and attached tetherout of the stomach through a first hole and back in through a secondhole. This can be effected by forming a tissue fold from the stomachwall or by utilizing a device that provides stitch-like functionality(see for example FIG. 23 a-c). The tether can be anchored to the tissueusing an anchoring element or the tether can be secured via knotting orthe like.

The tether can also include a stopper structure for limiting movement ofthe tether and/or anchoring element in an unwanted direction. Forexample, with reference to FIG. 13, in cases where tether 14 is anchoredthrough the stomach wall, e.g. when anchoring element 13 is positionedoutside the stomach against the serosa or in cases where tether 14 issecured through the tissue in an in-out-in configuration, a stopper 20can be provided on the tether to prevent movement of the tether in thedirection of the tissue, particularly as it has been discovered by thepresent inventors that the omentum tends to pull any objects, suchanchor 13, away from the serosa surface of the stomach. Additionally oralternatively, a washer can be used for preventing an anchor positionedagainst a tissue (e.g. a t-bar anchor) from burying into and eroding outof the tissue under the pulling forces of the tether. One configurationof such a washer is shown in FIGS. 23 a-c which is described in Example5.

Another embodiment of the present device includes a device bodyconfigured for at least partially residing within a pyloric canal andcapable of contacting a tissue region of the canal and/or modifying anopening size (as defined by, for example, cross sectional area orvolume) of the pyloric canal when a pyloric sphincter is open.Preferably, the device body is also capable of modifying an opening sizeof the pyloric canal when the pyloric sphincter is closed.

Such a device functions in activating mechanoreceptors present in thepyloric canal; reducing a maximal opening size of the pyloric canal whenthe pyloric sphincter is fully open and/or increasing the opening of thepyloric canal (i.e. preventing complete closure) when the pyloricsphincter is fully closed.

FIG. 5 a illustrates a pyloric device 100 (also referred to herein asdevice 100) which includes a device body 102 which is curved withopposing concave and convex surfaces (similar to a cashew nut) andattached anchoring mechanism (hooks shown). Device body 102 hasdimensions selected from a range of 1-4 cm in length (L, FIG. 5 a),0.5-2 cm in width (W, FIG. 5 a) and 0.3-2 cm in height (H, FIG. 5 a).Device body 102 can be fabricated from a variety of materials includingsilicone, polymers, ceramics and alloys or combinations thereof. Devicebody 102 can be solid or hollow; a hollow configuration can be filledwith a gas, liquid (e.g. saline), gel or different hardness solid.Preferably, device body 102 is made from a material soft enough to notcause erosion in the area of the pylorus, for example low hardnesssilicone.

An inflatable configuration of device 100 can include a port for fillingdevice body 102 which can be fabricated from a thin silicone shell, andas such at least one dimension thereof (e.g. height) can be adjustedbefore, during or following anchoring of device 100. Device 100 can bemade from a combination of flexible, inflatable and rigid components.For example, conduit 106 can be constructed from an inflatable innertube or bladder placed inside a rigid and non-collapsing outer tube tovariably set the minimum conduit diameter through the pylorus while body102 can be inflatable to adjustably block the maximum opening of thepylorus when open or the displaced volume of the region proximal to thepylorus, otherwise known as the pseudodiverticulum. This adjustabilityallows the doctor to optimize and balance the effects of prematuregastric emptying and slowed or less productive gastric emptying for eachpatient post implantation. Alternatively, body 102 can consist ofremovable insert elements that reside axially in conduit 106 and outsidebody 102 that when removed endoscopically increase the inner diameter ofconduit 106 or decrease the outer diameter of body 102 postimplantation.

Device body 102 serves to activate mechanoreceptors in the pyloric canalby applying (intermittent) pressure thereto, and/or to reduce the volumein the pyloric canal thereby reducing the opening of the canal when thepyloric sphincter is open. Such reduction can be in a range of 10-80%,preferably, 15-50%, most preferably 20-40%. Such a reduction of volumeslows down stomach emptying and contributes to a feeling of satiety in asubject.

As is mentioned hereinabove, device 100 can also function in modifyingthe opening size of the pyloric canal when the pyloric sphincter isclosed. When food enters the stomach, the antrum facilitates breakdownof food particles via repeated contraction waves, at the same time, thepyloric canal is closed to prevent passage of partially digest food intothe duodenum until the food is broken down by the mechanical action ofthe antrum. As is described hereinabove, it is believed that prematurestomach emptying (dumping) also contributes to early satiety. Devicebody 102 is preferably also configured to facilitate such dumping bymaintaining the pyloric canal partially open when the pyloric sphincteris closed. To enable such functionality, device body 102 is providedwith a conduit 106 which runs axially along the top, convex surface ofdevice body 102. Conduit 106 can be a partially open groove or channel(as shown in FIG. 5 a) or it can be a through-hole orifice (as shown inFIG. 5 b). In any case, conduit 106 maintains an opening through thepyloric canal when the pyloric sphincter is closed (as shown in FIG. 5 cfrom a side view in the narrow portion of the pylorus muscle P).

It will be appreciated that in the case of an open groove or channelconfiguration of conduit 106, the material of device body 102surrounding the groove is preferably rigid enough to resist bucklingwhen pressure is applied thereupon by the tissue. Such rigidity can beachieved via use of materials such as hard silicones, polymers, ceramicsor alloys or a combination of such hard materials coated with softshells fabricated from, for example, silicone rubber, PTFE and the like.Some elasticity and a curling motion in a region of device body 102surrounding the groove can be tolerated as long as an orifice ismaintained within the pyloric canal upon closing of the pyloricsphincter.

One distinct advantage of having an open groove/channel design issubstantial reduction in blockage. In cases where such groove is blockedby food particles when the pyloric sphincter is closed, subsequentopening of the sphincter and pyloric canal will release food particlestrapped within the groove/channel of conduit 106.

As is mentioned hereinabove, device 100 further includes an anchoringmechanism which in this configuration is attached to device body 102.The anchoring mechanism serves to anchor device body to tissue withinand/or adjacent to the pyloric canal. Anchoring mechanism can be used toanchor device body 102 to tissue within the pyloric canal and/or antrum,preferably anchoring is to the submucosa and or muscle layers.

The anchoring mechanism can be any mechanism which can be used to anchordevice body 102 to tissue such as mucosa, submucosa and/or muscle. Hooks108 are shown in the device depicted in FIG. 5 a. Although four hooksare shown in FIG. 5 a, it will be appreciated that any number of hooksarranged in any pattern along the concave surface of device body 102 canbe used for tissue anchoring. Other anchoring configurations which canbe used by device 100 include one or more pins 109 which can be insertedthrough guides disposed within device body 102 and tissue (shown in FIG.5 d from a side view in the narrowest portion of the pylorus P), sutureswhich can be used to suture device body 102 to the tissue, elastictethers (further described hereinbelow), deployable anchors such asthose shown in U.S. patent application Ser. Nos. 11/172,082; 10/726,011and 09/871,297 or any combination thereof. Pin 109 can be made of aflexible/elastic material, examples including silicone-covered NiTinolwire, or a braided polyester suture material. Anchors 108 can be afabricated from a tissue-penetrating material that that swells afterimplantation and more firmly anchors itself in the tissue with minimumtrauma. Anchors 108 can have ends that are inflatable to preventdislodging. Anchors 108 can interlock with one another in the tissue toincrease the strength of the anchor mechanism. Such anchors can becoated with fibrosis-inducing agents so as to induce local tissuefibrosis and enhance anchoring and/or with anti-microbial agents inorder to prevent possible infection of anchor site. Anchors 108 can becoated with an elastic or tissue adhesion material to encourage sealingof the submucosa around the anchor thereby reduce the inflow of acid orgastric juices from entering the underlying muscle layers and causingulceration.

Device 100 can be anchored to one side of the pyloric canal through oneor more anchors which can attach to tissue of the pylorus and/or antrum.Such unilateral or tangential anchoring is advantageous in that thedevice is not subjected to multiple radial forces applied by the openingor closing of the pyloric canal, thus, device 100 simply rides with thepylorus tissue through opening/closing cycles and does not affectpyloric sphincter function rather only pyloric canal opening size. FIG.5 e shows device 100 from the perspective of looking at the pylorus Popening from the stomach in an open pylorus and in FIG. 5 f in a closedpylorus. Note that device 100 doesn't experience significant radialforces when the pylorus is open and therefore is more likely to stayimplanted without eroding out or causing damage to the surroundingtissue.

FIGS. 5 g-h illustrate from a similar perspective an alternativeconfiguration of device 100 of the present invention. In thisconfiguration, device body 102 includes three semi circular members 110which can be separately anchored or interconnected through a unifiedanchoring support into the pylorus P tissue and optionally extendinginto the antrum and/or duodenum as parallel volume occupying elements.Each member 110 is positioned at a different radial region of thepyloric canal. When the pyloric canal is open as in FIG. 5 g, members110 limit flow through the canal to a region between members 110. Whenthe pyloric sphincter is closed as in FIG. 5 h, members 110 contact eachother and an orifice is formed between members 110 thus maintaining thecanal slightly open. In this embodiment, much of the grinding andrubbing in the pyloric region is transferred to the members 110 whichrub against each other and not the pyloric tissue directly, therebyminimizing erosion of the tissue in the area.

In an embodiment related to that shown in FIGS. 5 g-h, device 100consists of up to 1,000 members 110 that are effectively like littlespaghetti noodles 1-7 cm long that are tethered at one end of thepyloric muscle and at the other end at the distal antrum using anchors108. Alternatively members 110 can be anchored at only one end, eitherthe pyloric or antral and stretch or compress freely with the stomachcontents and normal peristaltic motion. Movement of members 110 throughstomach activity can activate mechanoreceptors present in theantrum/pyloric canal/duodenum leading to feedback control over eating.Members 110 can be made from a flexible material, such as, silicone, andbe anchored at on end only in the submucosa or in the muscle layers witha single anchor 108 each or tether 116 and ball 118 as is describedhereinbelow. Each member 110 can have a round, oval, square,rectangular, triangular or irregular cross section and also vary inwidth, shape and/or thickness along their length. Members 110 can behollow and filled with a gas, liquid or a gel to increase their volumesand/or compliance along all or part of their length. The gaps betweenthe members 110 may allow for chyme to pass through a closed pylorus andmay also serve to partially block the pyloric aperture and fill thepseudodiverticulum volume when the pylorus is open. The advantage ofmultiple members 110 is that the force on each member 110 is relativelysmall and therefore the anchoring can be shallower, perhaps into thesubmucosa layer only, and hence simpler. Furthermore, should any anchor108 fail, there will remain sufficient members 110 in the region toperform the function of device 100. Dislodged member 110 will passharmlessly through the digestive system. Furthermore, device 10including a plurality of members 110 will not be blocked by foodparticles because members 110 will be free to spread apart and rearrangethemselves as the pylorus opens and closes and based on the prevailingaxial flow of food through the pylorus. Assuming that each member 110 is1 mm in diameter and that the maximum pyloric opening on average is 10mm in diameter, then a quantity of approximately one hundred members 110would fill the pyloric opening and effectively completely block it. Inpractice, one would only want to partially block the pyloric opening, soperhaps only 25 to 50 such members 110 would be needed to block thepylorus by 25% or 50% respectively. Anchor 108 can take the form of Tanchor or a ball 118 which can be inserted via a punch across thesubmucosa layer, which is not connected rigidly to the stomach musclelayer. Anchor 108 can also take the form similar to the anchoring systemof a tape worm which has miniature teeth at the head of the tape wormthat bite into the submucosa at varying angles and prevent dislodgement.Such anchors could be preloaded and activated only once inside thestomach, allowing a subject to swallow a capsule containing members 110that are then activated to anchor to the stomach lumen without furtherintervention. Anchor 108 can also be a rigid needle-shaped element thatswells upon implantation and provides anchoring support. Anchor 108 canbe forcibly projected or shot into the tissue, or sutured or clipped inplace. Anchor 108 can take the form of a screw/helix made of abiocompatible or bioresorbale material, PLGA for example, which isscrewed into the submucosa or underlying muscle layer. In the case of abioresorbale material, the screw head of anchor 108 can dissolve andleave behind an elastic ball 118 which keeps element 110 permanently inplace. Element 110 or tether 116 can have elastic consistency andtherefore provide a seal around the hole in the submucosa layer andprevent acid or gastric juices from leaking into the underlying musclelayers. Implantation of device 100 in this embodiment can be effectedendoscopically by pushing in all of the anchors 108 of members 110simultaneously into the tissue proximal to the pylorus preassembled in aradial pattern around the pyloric opening or else served up in a“magazine” format inside the stomach and anchored one at a time. In thelatter embodiment, once hundred members 110, each 2 cm long and 1 mm indiameter, can fit single file end-to-end into a hollow tube, say 1.2 mminner diameter and 2 meters long that fits into the working channel of astandard gastroscope and are presented with the anchor side first to thetip of the working channel. Anchor 108 is secured into the tissue, theendoscope is then retracted 2 centimeters, member 110 is pulled out ofthe tube and remains tethered to stomach tissue by anchor 108, and thenext member 110 is presented to the tip of the working channel of theendoscope and the cycle repeated until sufficient members 110 have beendelivered into the pyloric region. Alternatively, member 110 can be acontinuous rod of elastic material, for example silicone, that isintroduced within the working channel or a gastroscope or alongside itin a separate tube and each member 110 has a portion of itself insertedand anchored into muscle tissue by a needle in the working channel ofthe gastroscope that works like a sewing machine, and that also cuts thecontinuous rod into smaller segments after inserting them, and thengrasps the cut end to insert in the next location. The elastic force ofthe stomach tissue surrounding member 110 may be sufficient to anchormember 110 in the tissue without the need for anchors 108 or tethers 116and balls 118. As a peristaltic wave flows through the tissue and thetissue tightens, it may also sufficiently compress and tightly gripmember 110 to avoid member 110 from being pulled out of the tissue.Furthermore, member 110 can protrude just slightly outside the stomachlumen, in which case the omentum surrounding the serosal surface of thestomach will likely latch on to the end of member 110 external to thestomach and anchor it in place. Experiments done by the inventors haveshown that the omentum acts to pull objects protruding through thestomach wall away from the stomach surface. Member 110 can have aprotrusion or feature on it to prevent it from being pulled out of thestomach altogether by the omentum, thereby creating stable anchoring ofmember 110 or the entire device in general.

FIGS. 5 i-j illustrate another alternative configuration of device 100of the present invention. In this configuration, device body 102 isshaped as a pillar/column which is sized and configured for spanning adiameter of an open pyloric canal (1-2 cm) and is designed for flexibleattachment at one or preferably two ends 114 through anchors or hooks108 into the pylorus P tissue. Such a configuration is fabricated fromrelatively soft materials (shore A hardness 5 to 60) which canbend/buckle upon application of radial force or from hard materialfabricated with a bending/buckling mechanism (e.g. hinge). In such aconfiguration, device body 102 bulks the pyloric canal when open (FIG. 5i) and bends/buckles to maintain the canal open when the pyloricsphincter is closed (FIG. 5 j).

The design of FIG. 5 i can be modified with a slit 116 which is closedwhen the canal is open (FIG. 5 k) and open to create a conduit 106 (FIG.5 l) when the pyloric sphincter closes.

FIGS. 5 m-n illustrate yet another embodiment of device 100 of thepresent invention. In this embodiment, device body 102 is shaped as aspiral spring-like element with attached hooks 108. Device body can befabricated from any elastic material or material combination (e.g.NiTinol covered with silicon). Such a spiral configuration can beconfigured such that device body 102 moves and accommodates any movementof the tissue attached thereto. Thus, when the pyloric canal is open,device body 102 can be stretched across the pyloric canal distancingeach spiral from the next, while when the pyloric sphincter is closed,the spirals can compact to form a hollow tube with conduit 106. Bulkingwould be provided by the thickness of the material forming the spiral(FIG. 5 l), while conduits 106 are formed by features on the compactedspirals (FIG. 5 m).

FIG. 6 a depicts in a cross section of the narrowest portion of thepylorus device 100 which is made from a soft material, such as siliconerubber. In this embodiment, device 100 having body 102 and optionallyconduit 106 is anchored to the tissue through a single elastic orinelastic tether 116 with an anchor (e.g. ball 118 shown in FIG. 6 a) atthe end. Based on the length, stiffness and shape of tether 116 and thesize and shape of body 102, device 100 is designed to either stay in theduodenum, stay in the pyloric canal, stay in the antrum, or shuttlebetween any and all of these locations. Device 100 in this embodimentcan be made from a single material, for example silicon rubber. Tether116 is implanted through the stomach side of the pylorus P submucosaand/or muscle and ball 118 emerges at the duodenal side of the pyloriccanal and keeps tether 116 from pulling out of the pyloric tissue andhence device 100 localized to the pyloric region. Tether 116 ispreferable elastic and therefore stretches and contracts inside thepyloric muscle. Tether 116 can also be textured or be covered with amaterial that will increase adhesion to the pylorus P submucosa and/ormuscle. Inside body 102, tether 116 and/or ball 118 can be a stifferframe material, such as NiTinol, that increases the rigidity of all orpart of device 100.

FIG. 6 b depicts a further embodiment of device 100 in which body 102 issupported by two (or more) distinct tethers 116 with balls 118. Tethers116 are flexible enough to not constrict the pylorus P muscle from fullyopening, but act only to keep body 102 aligned in the pyloric region.Body 102 can be solid, have a through hole conduit or consist ofinvaginated conduits 106, as shown in a head-on perspective in FIG. 6 cthat allow for passage of food even when the pylorus is closed. Body 102can vary in axial dimensions from the thickness of a membrane,approximately 1 mm thick, to a long tube approximately 5 cm long thatextends from the distal antrum into the duodenum as shown in FIG. 6 b,or any length in between. The second tether 116 can additionally oralternatively anchor device 100 to the distal antral region of thestomach.

FIG. 6 d depicts a further embodiment of the present invention wheredevice 10 comprises multiple volume-occupying bodies 102 flexiblyinterconnected via tethers 116 and ball 118 to pylorus muscle P andresides in the distal antrum DA. Bodies 102 occupy space in the volumedistal to the antral contraction waves (ACW) and partially obstruct thepyloric aperture (PA) or shuttle through the pyloric aperture into theproximal duodenum (D). FIG. 6 e is yet another embodiment wherein body102 is a space occupying entity that is anchored through two tethersinto the pylorus muscle P, separated either radial or circumferentially,and resides in the distal antrum DA. Body 102, which ranges in size from0.5 cm to 10 cm in diameter, preferably approximately 2 cm in diametercan be made of medical grade silicone, for example, and can be solid orhollow (hollow shown in FIG. 6 e), in which case it can be filled with agas, liquid, gel or a different solid used to provide body 102 with theproper flexibility to adjust to the complex and dynamic geometry of theGI tract in this vicinity. Body 102 can be sized to be approximately 2.5cm or larger so as to not pass through the pyloric aperture (PA) inwhich case it will be intermittently pushed up against and effectivelyseal the aperture or pyloric canal in each attempt of the antrum toempty a bolus of chyme into the duodenum. Alternatively, body 102 can besmall enough, approximately 1 cm diameter or smaller, to pass readilythrough an open pylorus and then “snap” back into the duodenum due tothe force of elastic tether 116, thus being shuttled between theduodenum and antrum. Body 102 can optionally contain conduit 106 toallow chyme to pass through the closed pylorus as described elsewhere inthis application. Tethers 116 and ball 118 can also be made of flexiblematerial such as silicone so that the anchors keep body 102 in theproper position against the forces of normal peristaltic motion. FIG. 6f depicts a further embodiment wherein device 100 comprises a hollowvolume-occupying body 102 which is anchored into the distal antrum in atleast one location in order to resist migration through the distalantrum DA through the pyloric aperture PA. In FIG. 6 f, two such axiallydistinct anchoring locations are shown. Body 102 is elastically/flexiblyanchored to the pylorus muscle (P) and a section of the antrum, in thisexample the antral muscle (AN) through elastic tethers 116 and balls118. Device 100 can consist of a plurality of such devices implanted inparallel that rub up against each other and against the canal when thepyloric canal is closed and then are separated when the canal is open.Body 102 can consist of a solid “tail” or hollow conduit 106 thatextends distal through the pyloric aperture PA and may even extend intothe duodenum to facilitate dumping as described elsewhere in thisapplication.

FIG. 6 g depicts yet a further embodiment where device 100 is made oftubular body elements 102 that extend from the distal antral (DA) sideof the pylorus (P) into the duodenum (D). Device 100 can be solid oralternatively have invaginated conduits 106 (similar in cross section tothe device of FIG. 6 c) to enable chyme to pass through a nominallyclosed pylorus. Device 100 is anchored using one or more flexibletethers 116 with or without an anchoring ball 118 to further anchordevice 100. Tether 116 can be implanted endoscopically using the methodsdepicted elsewhere in this patent. Once device 100 is anchored into thepylorus muscle, body elements 102 are pushed through the pylorusindividually using the endoscope or by normal peristaltic action. Onceon the duodenal side of the pylorus, body elements 102 are too big tocollectively pass back through the pylorus towards the antrum oralternatively they apply gentle pressure against the duodenal wall orthe duodenal side of the pylorus and prevent device 100 from migratingback into the antrum, even in the case of duodenal reflux into theantrum. At the same time, tether 116 prevents device 100 from passingfurther into the duodenum against peristaltic motion and keeps device100 in the pylorus region. Device 100 can therefore bulk the pyloricaperture thereby slowing down gastric emptying (based on the solidvolume of device 100) and also prevent the pylorus from sealing properlytherefore inducing dumping (based on the size and number of conduits106). Device 100 in this embodiment can be removed by simply pulling itout with the aid of a grasping tool introduced through an endoscope.Device 100 of this embodiment can made of a single piece of flexiblematerial, for example silicone rubber and be either solid or hollow.Device 100 can also be anchored in the distal antrum using through andthrough anchoring or an anchoring scheme totally internal to the GIsystem as described elsewhere in this patent.

In a further embodiment, an additional approach for anchoring device 100is to utilize a magnetic clasp. For example, and referring to FIGS. 6a-g, tether 116 can terminate on the side distal to body 102 with anembedded or exposed magnetic element or metal plate. Body 102 also hason its distal side a magnetic element or metal plate. When the twomagnets or alternatively the magnet and metal plate are in proximity,tether 116 and body 102 latch together and stay adhered, thereby loopingdevice 100 around the tissue. This latching can occur blindly withoutthe need for exact alignment in the duodenum. Furthermore, the magneticor metallic element in tether 116 can be sharpened and used as a selfboring trocar that goes through the tissue when pushed from behind. Sucha magnetic clasp can be instead of or in addition to ball 118 used foranchoring.

Alternatively, in a further embodiment, tether 116 can latch onto body102 with a self-aligning latch, much like the tongue of a tie-wrapenters into a one-way latch mechanism. A jig can be used to align tether116 to latch mechanism attached to body 102.

Alternatively in a further embodiment, tether 116 has a wire or othertension member running through it that when pulled from the antral sidecompresses a hollow ball 118 and flattens it, essentially increasing thecross-sectional area of ball 118 and preventing it from being pulledthrough the tissue.

Alternatively, in a further embodiment, tether 116 is introduced fromthe duodenal side using a back-facing needle and then pulled forwardtowards the antrum and connected to body 102 using any of the magneticclasps or latching mechanisms described above or known in the art.

Since device 100 can maintain the pyloric canal partially open when thepyloric sphincter is closed, device 100 of the present invention canalso include a valve mechanism to prevent backflow from the duodenum tothe stomach. Such a valve mechanism can employ one or more soft flapswhich are positioned within conduit 106 or incorporated into device body102. Such a flap can be designed capable of resisting reflux (from theduodenum to the antrum) and yet substantially not obstruct flow from theantrum to the duodenum.

For the purpose of demonstrating the function of one embodiment of theanchored device of the present invention, a representative sequence ofgastric emptying events as manifested in the antral/pyloric/duodenalregions is illustrated by FIGS. 2 a-c described above. The function ofdevice 10 with respect to these events is illustrated in FIGS. 2 d-f.

The invaginated cross section of device 100 as show in FIG. 2 e can actto make the pylorus “leaky” and force some of the undigested contents ofthe pseudodiverticulum (PD) into the duodenum (D) prematurely(designated by the arrow in FIG. 2 e) thereby reducing the lag time ofsatiety feedback signals and providing duodenal biochemical, neuronaland hormonal feedback signals that slow gastric emptying. Alternativelyor additionally, the bulk of the flexible body of device 10 can projectinto the pseudodiverticulum PD as shown in FIGS. 2 d and 2 e(corresponding to the same stages of FIGS. 2 a-b without device 100),thereby reducing the effective volume of chyme in thepseudodiverticulum. The bulk or volume of device 100 takes the place ofchyme in the pseudodiverticulum PD and therefore causes less chyme toenter into the duodenum D, making each evacuation cycle less productiveand hence slowing gastric emptying.

During this evacuation stage, the bulk of the cross section of device100 positioned in a patent pylorus acts to partially block or restrictthe flow of chyme through the pylorus and therefore slow gastricemptying. The body of device 100 is flexible enough, for example a softsilicone shell filled with a gas or saline, to conform to the narrowgeometry of the pyloric canal PC. Device 100 can be anchored using anymethod described in this patent application to the pylorus (P) and/ordistal antrum (A) to keep device 100 positioned in the pyloric canal(PC) without being forced into the duodenum D. When the cycle of FIGS. 2a-c repeats itself, device 10 reforms into its original shape shown inFIG. 2 d and the cycle is repeated.

The device of the present invention can be effective at both theevacuation and retropropulsion phases of digestion. By controlling thegeometry or cross section of a device, one can control the amount ofdumping by, for example, increasing the extent of intentional mismatchbetween multiple devices, increasing the invagination of the device bodycross section, or increasing the diameter of a hollow straw-likepassageway of chyme through a closed pylorus). Likewise one can slowgastric emptying during evacuation by increasing the cross sectionalarea or bulk of the device to decrease flow or partially displace thevolume of chyme in the pseudodiverticulum. The proper tradeoff for thesetwo effects can provide the optimal effect in a patient. Furthermore,the device can be adjustable, say with inflatable chambers, so that theproper geometry will be set only after implantation and adjusted in realtime for each patient.

As a further feature of the device, the blockage of the pylorus by thebody of the device could block and better seal the pylorus therebyreduce the amount of bile reflux resulting from bile acids flowing intothe antrum through a patent pylorus. This device could help relieveulcerative gastritis or change the chemical properties of the chyme insuch a way as to cause malabsorption or trigger a duodenal feedbackresulting from less well digested chyme entering the duodenum.

Device 100 of the present invention can also be configured capable ofaffecting stretch receptor function at the pylorus region therebyfurther facilitating early satiety. Studies have shown that stretchreceptors have an especially high density in the pylorus, and respond atlower levels of stretch than those of the antrum [Ramkumar and Schulzeet al. Neurogastroenterol Motil (2005) 17 (Suppl. 1), 22-30]. Motorfibers of the vagus mediate stretch-mediated pyloric responses byreleasing enkephalins and acetylcholine and inhibitory responses throughthe vasoactive intestinal peptide (VIP) and nitric oxide (NO). Thus,device body 102 can also effect stretch receptors present in pyloriccanal tissue by physically opening and stretching the pylorus and theclose by duodenal and antral tissues, which in turn can trigger thefeedback mechanisms listed above to alter gastric emptying.

Device 100 can be inserted into the pylorus using a variety oftechniques. Example 1 provides further description of one possiblepositioning and anchoring approach which can be used along with device100 of the present invention.

As seen in FIG. 9, the general method of anchoring a soft tetherdescribed in Example 1 can be useful for anchoring other devices,including element 136, which can be a sensor, actuator, electricalmechanical or chemical stimulator, drug depot, or amagnetic/paramagnetic attachment point (as described more fullyhereinunder), is attached to ball 118 on a tether 116 and is anchoredinside muscle layer 140 between the serosa 138 and submucosal layer 142.The anchoring can also be through submucosa 142 without penetratingmuscle layer 140 to allow the implanted device to move with submucosa142. Alternatively, the anchoring can be through the serosa 138 as well.Such anchoring can be effected with a curved version of punch 132 and134 as described in Example 1. Such anchoring can also be effected bythe methods and devices described in FIGS. 21-25. Element 136 can be anydevice known in the art that is useful when positioned long term in thestomach.

The configuration shown in FIG. 9 can be used as a part of a systemdesigned for retaining active agents in the GI tract. Such a system caninclude three components, an anchored retention element residing in theGI tract (as shown in FIG. 9), a carrier that is taken orally and isdesigned for interacting with the anchored retention element, and anactive agent contained in or formulated with the carrier. As an exampleof this embodiment, the device body can include a magnetic orparamagnetic retention element to which would automatically attachthemselves magnetic or paramagnetic carriers that are introduced orallyand that can be coated or filled with an active agent as above. In thisembodiment, the device is anchored to the GI tissue of interest usingany of the techniques described herein, at any point along the GI tractfrom the mouth to the anus where the release of an active agent isrequired. Following anchoring of the retention element, the subjectswallows a carrier composed of magnetic or paramagnetic particle orparticles, preferably any size from nanometers to a centimeter in size,which attach onto the device body due to magnetic forces. By way ofexample, the anchored retention element can be a sintered steel disc andthe active compound coated onto micro or nano-particles of magneticmaterial that will fill the pores of the steel disc. The active agentcontained in or around carrier would elute off into the GI system in aclosed-loop or open-loop manner and over a time period longer than wouldbe achievable if the active agent was swallowed without being attachedto device body. The active agent is replenished by having the subjectswallow another such carrier at a later time that would also attachitself to the device body.

The release of the active agent from the carrier could be controlled viaopen (no device feedback) or closed (device feedback) loop feedbackmechanisms using a variety of sensors, actuators, extended release drugformulations, and passive and active drug depot technologies known inthe art. Control of release can be effected from within the retentiondevice, the carrier, or from a separate command issued from within orfrom outside the body by the subject, health care professional or anyother sensor. For example, a satiety hormone could be released into theduodenum in a controlled manner any time stomach acid production issensed. Alternatively, the packaging or polymer containing the activeagent could degrade in a controlled fashion thereby releasing the activeagent in the presence of acid so that no sensor would be required. Sucha device, when anchored in the small intestine for example, can be usedto release a drug (e.g. an immune modulator) for a disease (e.g. Crohn'sdisease) in an open loop continuous manner over a long period of timewhere such a drug might not easily survive the passage through thestomach (e.g. a peptide) and when repeated administration isinconvenient or not practical. Another example would include diabetestherapy effected by insulin released into the small intestine using acontrollable depot of insulin attached to the device body with therelease triggered using an implanted or external glucose sensor ormanually controlled by the subject.

The present invention envisions that any drug, regardless of the currentform of delivery, can be formulated to reside in a carrier to beretained by an anchored retention device for extended or controlledrelease in a convenient and safe manner. In addition to magnetic orparamagnetic forces, other forces can be used to attach the active agentto the device body such as hydrophobic interactions, van der waals,electrostatic, colombic, antibody, biotin-avidin, covalent,crosslinking, size exclusion, affinity, electromagnetic or mechanicalinteractions (e.g. a form of Velcro™). The method of attachment can bereversible in a controlled or uncontrolled manner. For example, theactive agent could be contained in a carrier capsule or particle thatattaches to the device body for a set period of time and then detachesautomatically (due to known off-rates of the attachment mechanism, theaction of a timer or the acid degradation of a linker for example) orvia remote control actuation, making room for the next carrier capsuleintroduced into the GI tract. Alternatively, new carrier particles canaccumulate on top of old and depleted carrier particles as would be thecase of magnetic forces. Once treatment ceases or once the binding siteson the device body are fully occupied, the carrier capsule, the entiredevice or just the device body can be removed from the GI tract usingtechniques described elsewhere in this patent application. Furthermore,instead of an active agent, the retained carrier can include a temporarybiosensor or camera for example for measuring a parameter of the GIsystem for a period of time longer than would be permitted if thebiosensor or camera would be subject to the normal peristaltic forces inthe GI tract. Other devices, such as RFID, identifying tags, spaceoccupying devices, stimulators with fixed battery life or flow reductionelements, can be attached to the anchored retention device using such areversible linking scheme and replenished through a simple oralingestion of a new carrier. It is also envisioned that such an activeagent retention system can be utilized for other lumens in the body forsimilar effects, for example for long term release of an active agent,alteration of flow or measurement of parameters in the vascular system.

The present invention can be used for treating a variety of conditionsand disorders which are associated with eating. As used herein, the term“treating” includes abrogating, substantially inhibiting, slowing orreversing the progression of a condition, substantially amelioratingclinical or aesthetical symptoms of a condition or substantiallypreventing the appearance of clinical or aesthetical symptoms of acondition.

Conditions and disorders associated with satiety include, but are notlimited to, obesity and obesity related disorders such as for exampleanorexia and bulimia. Furthermore, use of the present device couldprecondition patients that are candidates for bariatric surgery as asimple way for weight reduction prior to surgery, and by providing anadjustment period for managing dumping syndrome symptoms.

Example individuals who may benefit from the present device forconditions other than eating disorders or obesity are described below.

Gastroparesis is abnormal functioning of the stomach without anyphysical evidence of obstruction, a debilitating condition which ismainly a complication of diabetes. Other etiologies include: (a)Parkinson and other neurological conditions (b) post vagotomy withpyloroplasty and other gastric surgeries (c) immune diseases such aslupus and scleroderma; and (d) gastric scaring due to past ulcers.Current treatments of these conditions vary from extensive life styleand diet modification through pro kinetic medications and electricalstimulation. Keeping the pylorus open using the device illustrated inFIGS. 5 a-c would serve to accelerate gastric emptying in these patientsand significantly ameliorate the symptoms of the disorder.

Peptic ulcer disease (PUD) is an ulcer occurring near the pylorus thatmay cause strictures as a result of the inflammation. These patientsafter eradicating the cause of the ulcer may benefit from a device thatkeeps the otherwise narrowed pylorus open.

Post major abdominal surgical patients often complain of delayed gastricemptying symptoms. They may benefit from an open pyloric sphincter thatkeeps the flow of gastric secretions and food. In such patients, theneed for the device may be temporary, and therefore the ability ofremoving the device or having it degrade and detach over time would bebeneficial.

Hypertrophic pyloric stenosis (HPS) patients suffer from mechanicalgastric outlet obstruction, and may benefit from a device capable ofkeeping the pylorus open.

To treat the above described disorders, the device of the presentinvention can be implanted in the stomach of a subject using one of theapproaches described herein. The device is implanted for a time periodwhich is determined according to parameters assessed by the treatingphysician. Such parameters can include, the condition of the subject(e.g. severity of obesity), the eating habits of the subject, theintended purpose of the device (e.g. degree of weight loss desired) aswell as other parameters. In any case, treatment is terminated by simplyremoving the device as described herein, or by enabling device selfremoval (e.g. using an anchor which is degradable over a predeterminedtime period).

As used herein the term “about” refers to ±10%.

Additional objects, advantages, and novel features of the presentinvention will become apparent to one ordinarily skilled in the art uponexamination of the following examples, which are not intended to belimiting. Additionally, each of the various embodiments and aspects ofthe present invention as delineated hereinabove and as claimed in theclaims section below finds experimental support in the followingexamples.

EXAMPLES

Reference is now made to the following examples, which together with theabove description, illustrate the invention in a non limiting fashion.

Example 1 Anchoring of a Pylorus-Attached Device

Device 100 can be inserted into the pylorus using a variety oftechniques. For example, with reference to FIG. 7 a, device 100 asdepicted in FIG. 5 b can be delivered at the end of an endoscope in atube 120 with an open bottom 122 wherein the body 102 of device 100 isloaded against spring 124 that naturally concaves downwards but is heldconcave upwards by pin 128 running in a constrained channel through tube120 and through retaining loops 126. Tube 120 (with anchors 108retracted in tube 120 so that they cannot damage surrounding tissue) ispositioned in the narrow apex of the pylorus P and pin 128 is pulled torelease retaining loops 126 which in turn releases body 102 and spring124 to the concave downward position, wherein anchors 108 are forced tobite into the pylorus tissue and anchor device 100 in the pylorus P(FIG. 7 b). Tube 120 is retracted leaving device 10 anchored andpositioned in the pylorus (FIG. 7 c). The same technique can be used toanchor devices in other GI tissue areas, such as the lower esophagealsphincter.

In the case of the embodiment described in FIG. 6 a-c, the insertion ofa tether 116 can be effected via an endoscopic procedure by using thedevice shown in FIG. 8 a-c. Tether 116 and ball 118 are supported by atwo piece punch 132 and 134 made from a hard material such as steel.Punch 132 and 134 penetrate tissue layer M (FIG. 8 a) all the waythrough the tissue, taking ball 118 and tether 116 along with them (FIG.8 b). Section 132 of the punch is then retracted followed by section 134of the punch leaving tether 116 and ball 118 inserted into the tissue M(FIG. 8 c). The process is repeated if more than one tether 116 is used.

Removal of device 100 can be effected using one of several approaches.Device 100 is removed (if needed) by simply pulling it out by detachingor overpowering ball 118, or any other anchor design used.Alternatively, ball 118 or tether 116 can be clipped via a clippinginstrument mounted on an endoscope and the device removed via a grasper.

Example 2 Implantation of the Present Device in Pigs

Four female pigs marked Shosh 7 to Shosh 10, approximately 3-4 monthsold weighing between 60-70 kilograms were selected for the implantationof 4 different configurations of the device of the present inventionmade of silicone. FIGS. 10 a-d illustrate the four configurations of thepresent device as implanted in the four pigs. Each device shown in thefigures was anchored to antrum tissue of a pig to achieve the anchoringpositioning shown therein. Thus, FIG. 10 a, depicts implantation in afirst pig (designated as Shosh 7 in this study) of a 40 mm long 1 cmdiameter cylindrical device body which was anchored in the antrum withan anchoring position and tether having a length enabling movement ofthe device body into the duodenum. FIG. 10 b represents similarpositioning in a second pig (designated as Shosh 8 in this study) of adevice body which includes a plurality of brush-like projections with ananchoring position and tether having a length enabling movement of thedevice body into the duodenum. FIG. 10 c depicts antral positioning in athird pig (designated as Shosh 9 in this study) of two device bodieshaving brush-like projections with an anchoring position and tetherhaving a length enabling movement of the device body in the antrum,while FIG. 10 d illustrates antral-duodenal (trans-pyloric) positioningin a fourth pig (designated as Shosh 8 in this study) of a 100 mm longdevice body having brush-like projections with an anchoring position,device body and tether having a length enabling movement of the devicebody all the way from the antrum into the duodenum.

Prior to device implantation, each pig was anesthetized and a standardelectrosurgical scalpel was used to make a 20 cm incision along themidline of abdomen to expose the stomach. The stomach was elevated tothe surface of the skin and an incision was made on the side surface ofthe stomach midway between the lesser and greater curvature starting 3cm proximal to the pylorus and extending for 5 cm along the antrum. Acurved taper-cut needle attached to a number 5 Ethibond™ braidedpolyester suture was inserted into the stomach cavity through thisincision and passed into the antral tissue on the exposed opposite wallof the stomach through the mucosa, submucosa and partially through themuscle layer and re-emerging into the stomach cavity through a 1.5 cmtunnel. The end of the braided suture was tied to an elastic tether madeof shore A 60 silicone 2 mm in diameter. The suture was used to pull thetether through the tissue tunnel. The suture needle was then insertedthrough a 1.5 cm diameter 2 mm thick “washer” made from shore A 60silicone and the tether was pulled through this washer as well. Thetether was attached on its other end to the device (whose geometry wasdescribed above). The device was located in the desired location in theantrum, duodenum or both, and the washer slid on the tether until ittouched the antral tissue on the proximal end of the tissue tunnel. Theelastic tether was then tied into 4 simple knots and the excess tethercut and removed. The stomach and abdomen were sutured closed withstandard absorbable sutures using standard operative techniques. Theexternal skin wound was closed with metal clips.

Results

The 4 pigs were provided with 4 days of recovery from the surgicalintervention prior to entering a solid feed consumption trial. The pigswere provided commercial solid feed in the form of pellets (Ambar,Israel), identical to the feed provided to commercially grown pigs.

The feeding regime of the 4 pigs throughout the trial was as follows:

-   -   (i) Pigs were fed twice a day, the first time at 06:00 and the        second time at 14:00.    -   (ii) In each feeding, every pig received 2 kg of feed, an amount        which exceeds their feeding capacity in one session. Thus actual        feed consumption is limited only by the appetite of the pig.    -   (iii) Starting from time zero (providing the 2 kg feed to the        pig), the feed quantity consumed was measured and recorded at 10        minutes, 20 minutes, 30 minutes, 45 minutes and 60 minutes.    -   (iv) Starting from day zero, the weight of each of the 4 pigs        participating in the trial was measured twice a week.    -   (v) On day 21 of the trial, an endoscopic procedure was        performed on each of the pigs, and the device was released from        its anchoring site, and then endoscopically retrieved from the        pig's stomach through their mouths.    -   (vi) The same feeding protocol used during days 0-21 of the        study, was used during days 22-33 of the study, when the devices        were no longer present in the pigs' GI system    -   (vii) On day 34, the 4 pigs were sacrificed and the study ended.

Observations of control female pigs (same genetic origin, same age andweight, with and without a sham operation) uncovered that the typicaldaily weight gain pattern of a commercially grown pig at a weight of 60Kg. is 600-700 grams per day, while the typical daily weight gainpattern of a commercially grown pig at a weight of 90 Kg. is 900-1,100grams per day.

Post implantation weight gain pattern of Pigs 1-4 (Shosh 7-Shosh 10) aregraphically illustrated in FIG. 11 (with the device present in the GItract of the pigs) and in FIG. 12 (following endoscopic removal of thedevice). During the period between days 0-21 with the devices implantedin their stomachs, the 4 pigs average daily weight gain was 460 gramsper day, 24%-36% lower than untreated, commercially grown pigs in thesame facility (see FIG. 11). During the period between days 22-33without the device in their stomachs, the 4 pigs average daily weightgain was 1,166 grams per day, 6%-29% higher than untreated commerciallygrown pigs in the same facility (see FIG. 12). Therefore the presence ofthe device in the GI tract of the pigs significantly slowed down theirweight gain.

Example 3 Implantation of a Through-Stomach Antrum-Anchored GastricDevice in Live Pigs

An eating behavior modification device with a silicone tether and apolypropylene T-anchor was anchored in an antral wall region of stomachsof female pigs using a dual-channel gastroscope. The delivery apparatusand attached device are shown in FIGS. 14-15. As is shown in FIG. 15,the device is secured to the applicator head of the delivery apparatusand the anchoring element of the device is secured within a grooveformed in the delivery needle. The needle is disposed within workingchannel 1 of the gastroscope while the tether is secured against theapplicator head by a snare-like element (retaining loop wire) which isdisposed within working channel 2.

To deliver the device, the delivery apparatus and loaded device wereguided through the mouth of an anesthetized pig through the esophagusand into the stomach.

Once the applicator apparatus and loaded device are positioned withinthe stomach, the needle is pushed through the stomach wall (FIG. 16)under direct visual guidance and the anchoring element and tether of theanchor are advanced through the wall tissue and the anchoring element isdeployed. In the configuration shown in FIG. 15, the 16 gauge hypodermicneedle is 10 mm long and the anchoring element is a t-bar made out of apolypropylene cylinder 1 mm in diameter and 6 mm long. Deployment iseffected via a plunger (push wire) disposed within the needle emergingat the operator end of the gastroscope. Once the needle and loaded t-baranchor are pushed through the stomach wall (FIG. 17), the plunger isdeployed to eject the t-bar anchor from the needle. Tension on thetether against the t-bar anchor aligns it against the tissue (serosa)and locks it into place (FIG. 18).

After the anchor is deployed, the needle is retracted back into theworking channel, and the device is released in the stomach.

The above described procedure was successfully conducted on severalpigs, in which the device was anchored to the stomach wall (FIG. 19 a)for 16 weeks from delivery to withdrawal. FIG. 19 b shows three suchdevices anchored in the stomach of a single pig that resided with nocomplications in the stomach for 16 weeks.

The animals were sacrificed at the end of the 16 week period and tissuesamples from the tissues around the anchoring sites were harvested,sectioned and mounted on slides.

FIG. 20 a is a microscopic image of a mounted tissue section showing theregion of anchoring (arrows); FIG. 20 b illustrates regions of thetissue section shown in FIG. 20 a which were further examined usinghigher magnification (FIGS. 20 c-h). The histological features aretypical of reaction to inert foreign matter. The degenerative changesobserved in the mucosa and the tunica muscularis are mild and within theexpected range for an area with low-grade inflammation. Thus, long termanchoring using the present anchor produces minimal tissue reaction andno adverse affects.

Example 4 Implantation of a Pyloric-Anchored Gastric Device in Live Pigs

The delivery apparatus described in FIG. 21 a-c and FIG. 22 a was usedto anchor an eating behavior modification device of the presentinvention to the pyloric sphincter muscle of an anesthetized 40 kilofemale pig. The delivery apparatus, designated 200 in FIGS. 21 a-c,includes an endoscope 60 (only distal tip shown) having one or moreworking channels 62 and preferably a camera 72 and/or a camera which cancurve back (˜180°) out of a separate endoscope working channel.Apparatus 200 includes a delivery device 64 (needle in FIGS. 21 a-c)which functions in carrying anchoring element 13 and delivering itthrough GI wall tissue or sphincter tissue. Delivery device 64 isdeployed and operated through working channel 62. Delivery device 64 canbe constructed such that when sequestered within the working channel ofan endoscope it does not substantially prevent bending of the workingtip of an endoscope. This can be achieved by using a short needle (e.g.10 mm) attached to a flexible pushrod or by fabricating the needle froman elastic alloy such as Nitinol. Apparatus 200 further includes anoptional alignment head 74 which is mountable on distal end of endoscope60.

Alignment head 74 has several functions. First, it allows the operatorof apparatus 200 to see the path that delivery device 64 will take whenpushed out or working channel 62. Second, it prevents delivery device 64from unwanted perforation of the lumen. Third, it provides a positioningaid and control over the depth and length of the insertion path foranchor 13 and tether 14 through tissue 82. In this way, device 10 can bepositioned at a known distance from the narrowest portion of a sphincteropening for example. Fourth it provides a counter force to the pushingof delivery device 64 given the endoscope 60 may not be rigid enough toresist such a pushing force without moving and therefore losing thecontrol and alignment of the insertion path of anchor 13 and tether 14into tissue 82.

Alignment head 74 is preferably flat (e.g. 1-3 mm thick) and optionallytransparent so as to not interfere with the operator's field of view asviewed through camera 72. Alignment head 74 is also flat in order toeasily enter a sphincter and enable alignment head 74 to fit all the wayagainst the annular ridge of a sphincter tissue without forcing thesphincter open. Delivery device 64 slides alongside alignment head 74until it reaches needle stop 78. Alignment head 74 can have a distal arm76 and optionally a proximal arm 80 used to position endoscope 60 aroundtissue 82 (in this case the ridge of a sphincter). Alignment head 74 canbe positioned against tissue 82 passively using the twisting and axialpositioning of endoscope 60 along with manipulation of the alignmentwheels of endoscope 60 and/or through vacuum means or other tissueapproximation means such as pullable helical or temporary anchorsconnected to alignment head between distal arm 76 and proximal arm 80.In some areas of the GI tract, there are natural convex tissue folds,such as along the angulus of the lesser curvature of the stomach, thatcan be used as a site of anchoring through the submucosa or through themuscle with the anchor and the device both being present in the GI tractusing the techniques described herein. The distance between distal arm76 and proximal arm 80 (or the distal tip of endoscope 60 in case noproximal arm 80 is used) determines the path length of delivery device64 in tissue 82. Likewise, the length of distal arm 76 and proximal arm80 determines the depth of insertion through the tissue of interest. Ashort depth (e.g. short arms of approximately 2-5 mm) would allow forsub-mucosal anchoring while a deep depth (e.g. long arms ofapproximately 5 mm or more) would allow for anchoring through muscle oreven penetration outside the serosa. The importance of the proximal arm80 is that the entry point of delivery device 64 into the tissue can bevisualized by camera 72 until delivery device 64 either hits needle stop78 or marker 84 on delivery device 64 is aligned with proximal arm 80(see FIG. 21 b). Without proximal arm 80, tissue 82 can press up againstcamera 72 and the operator of apparatus 200 may not be able to visualizethe insertion point of delivery device 64. All parts of alignment head74 are atraumatic with rounded corners and optionally flexible side toside to prevent tissue damage while being manipulated in the GI lumen.Examples of suitable materials for alignment head 74 is molded plasticor silicone covered metal wire.

Device 10 (made up of anchoring element 13 tether 14 and device body 12)can be pulled along the outside of endoscope 60 from outside the bodythrough the mouth and esophagus into the region of interest using afriction fit between anchor element 13 and the delivery device 64.Lubricant such as KY can be used to minimize friction of endoscope 60and device 10 through the passageway to the implantation site. Apparatus200 optionally includes an element 210 for securing device 10 toendoscope 60. Although device 10 can be introduced into the stomachseparately from the introduction of endoscope 60, using endoscope 60 tocarry device 10 into the stomach is preferred. Element 210 can be asnare or sheath which is deployable from working channel 62, analternative working channel or actuator means running alongsideendoscope 60. For example, a snare configuration can be realized bylooping a wire out of channel 62. Such a loop can be pulled from theoperator end of endoscope 60 through holes around the outside of a cupplaced on the distal end of endoscope 60 (such cups are used for polypsnares and band ligation for example) and used to secure (ensnare)tether 14 or device 50 against the body of endoscope 60 or the distalcup attached thereto. Once anchoring element 13 of device 10 isdelivered by delivery device 64, element 210 can be released to releasedevice 10 from apparatus 200.

To deliver device 10, alignment head 74 of apparatus 200 is positionedaround the ridge of tissue 82 as is illustrated in FIG. 21 a. Deliverydevice 64 is pushed through tissue 82 until reaching needle stop 78 oruntil marker 84 was aligned with proximal arm 80 as viewed by camera 72as in FIG. 21 b. Anchor element 13 is pushed out of delivery device 64using a flexible pushrod (not shown) running along the inside lumen ofdelivery device 64 and operated at the operator end of endoscope 60.Delivery device 64 is withdrawn back into working channel 62 ofendoscope 60 and apparatus 200 is removed from the stomach leavingdevice 10 anchored in tissue 82 as in FIG. 21 c.

The delivered device (10) functions in stimulating the antral andduodenal regions of the GI tract and is free to pass back and forththrough the pyloric opening on an elastic tether that anchors the devicewithin a few cm of the pyloric opening. The device body (12 in FIGS. 21a-c) is a molded cylinder with rounded ends made of silicone 10 mm indiameter and 25 mm long. The anchor and tether are made from one pieceof silicone shore A 60 hardness. The tether is 1.5 mm in diameter and 4cm long and the T anchor is 1 mm in diameter and 6 mm long with aNitinol wire 4 mm long and 300 microns in diameter running through thecenter of the silicone T to stiffen it and to provide a radio-opaquemarker of the anchor's position.

In the pig experiments described herein, delivery apparatus 200 employeda slotted 16 gauge 4 cm long hypodermic needle for delivering the deviceand an alignment head for guiding the trajectory of the needle throughthe tissue (FIG. 22 a). The needle was delivered through a workingchannel of a standard endoscope (Olympus GIF 130) while the alignmenthead was mounted on the tip of the endoscope. The alignment head waspositioned in the duodenum against the pylorus sphincter and thedelivery needle was pushed through the pyloric sphincter to the distalend of the alignment head as per the technique described in FIGS. 21 a-c(but without the proximal arm on the alignment head). The anchor wasreleased and positioned on the duodenal side of the pyloric sphincterwhile the tether emerges on the antral side and connects to the devicebody. The anchored device is pictured in FIG. 22 b. The procedure wasrepeated on a separate 40 kilo female pig with similar results.

Example 5 Anchoring Approaches

FIGS. 25 a-c illustrates in-tissue anchoring of the present device viascrew in coil anchors. Anchor element 13 in this case is a spring coilor soft tissue screw or auger made of metal or a polymer that is affixedto tether 14 and device body 12. Cup 88 protects the tissue from thesharp point of anchor element 13 and can also serve as a vacuum cup tohelp affix the tip of endoscope 60 to tissue 82 using vacuum means. FIG.25 a shows apparatus 200 approaching the anchoring position of tissue82. FIG. 25 b shows cup 88 in contact with tissue 82 and delivery device64 having screwed in anchor element 53 into tissue 82. FIG. 25 c showsdelivery device 64 detached from anchor element 53 and withdrawn backinto working channel 62 of endoscope 60. Device 10 (which is comprisedof anchor element 13, tether 14 and device body 12) is now anchored intotissue 82. Anchor element 13 can also be sized to fit completely withinworking channel 62 of endoscope 60, obviating the need for cup 88.Device 10 can be removed by cutting tether 14 or unscrewing anchorelement 13 using the reverse of the endoscopic procedure as thatdescribed above. Anchor element 13 can be made out of PLA, PGA or thelike and designed to biodegrade over time leaving only tether 14, withperhaps some protrusion or other anchoring feature, anchoring tether 14and therefore device 10 in tissue 82.

FIGS. 23 a-c illustrates a through-tissue anchoring of device 10 havinga t-bar anchoring element 13. In the case depicted in these Figures,tissue anchoring is effected through a tissue fold created by a vacuumchamber 204. Device body 12 is not shown.

Apparatus 200 is designed for mounting on an endoscope (not shown) andincludes a vacuum conduit 202 for communicating a vacuum force from avacuum device positioned outside the body to vacuum chamber 204.Apparatus 200 further includes a movable tissue piercing element 206(e.g. needle) which is designed for carrying tether 14 and anchoringelement 13 through the tissue fold.

Apparatus 200 is used as follows. A device 10 is loaded onto apparatus200 by placing anchoring element 13 within a groove in tissue piercingelement 206, optionally coupling device body 12 to apparatus 200 or theendoscope onto which its mounted and running tether 14 along tissuepiercing element 206 and body of apparatus 200. Device body 12 can becoupled to apparatus 200 or endoscope using an attachment mechanismwhich can be released by a cable running through a channel of theendoscope. Optionally, a soft (e.g. silicone) disc-shaped washer 208 ismounted within chamber 204 in the path of tissue piercing element 206.The washer serves to prevent tissue erosion or rip-through of the smallt-bar anchoring element 13 into the submucosal due to the tension ontether 14.

FIG. 23 a illustrates apparatus 200 with mounted device 10 as configuredprior to advancement of apparatus 200 into a stomach of a subject. Oncein the stomach, apparatus 200 and attached device 10 are maneuvered intoposition (e.g. wall of the antrum) using the endoscope mounted camera.Alternatively, apparatus 200 can be without visualization means and aseparate imaging gastroscope (e.g. a “baby scope”) inserted in parallelcan used to image the position and function of apparatus 200. Vacuumchamber 204 is juxtaposed against the mucosa of the antrum and 650 mm Hgof vacuum is created therein using a 10 gage Teflon tube insertedthrough a second working channel of the gastroscope or parallel to asingle channel gastroscope and connected to a vacuum pump. Vacuumchamber 204 can optionally contain multiple vacuum channels runningalong the top or sides of the chamber or multiple vacuum ports to allowfor uniform distribution of vacuum along the entire length and breadthof the vacuum chamber. Such channels or multiple ports will not besealed by the tissue upon it being sucked into the vacuum chamber andtherefore allow for the suctioning of a uniform volume of tissue intothe vacuum chamber. Alternatively, the top and sides of vacuum chambercan be formed from channels or tubes with a screen or porous meshmaterial to allow for uniform distribution of the vacuum force along thevacuum chamber volume without having any one point of vacuum entrancesealed by the tissue and therefore block the vacuum reaching other partsof vacuum chamber 204. A tissue fold 82 1-15 mm deep, preferably 5-10mm, is pulled into vacuum chamber 204 under the negative pressure of thevacuum and tissue piercing element 206 is pushed by the operator todrive anchoring element 13 and attached tether through tissue fold 82and through washer 208 to the distal end of vacuum chamber 204.Following tissue piercing, anchoring element is ejected from tissuepiercing element 206 using an internal pushrod (not shown) and piercingelement 206 is retracted back into the working channel of the endoscope.Vacuum in chamber 204 is released and apparatus 200 is removed from thestomach leaving behind device 10 anchored with anchor 13 through washer208 in tissue fold 82 as shown in FIG. 23 c. It is also envisioned thatwasher 208 can have the tether and device body attached to it and thatboth ends of tether 14 terminate with anchor element 13, thereby leadingto a “forward anchoring” configuration.

Example 6 Implantation of an Antrum-Anchored Gastric Device in Live Pigs

Three female pigs approximately 2-3 months old weighing between 45-50kilograms were selected for implantation of the device shown in FIGS. 23a-c. The pigs were anesthetized and apparatus 200 described above fittedon an Olympus GIF 2T100 dual channel gastroscope which was used toimplant device 10 in antrum tissue. The piercing element 206 was an 18gauge needle 3.5 cm in length. Anchor element 13 was a t-anchor made of21 gauge hypodermic tubing 6 mm in length attached to 25 mm of 00Ethibond™ polyester braided suture which was run through a hole groundinto the center of the t-anchor, run out one of the sides and then heatmolded into a ball that would not fit back through the open end of thet-anchor tube. On its other end, the braided suture material wasattached to a smaller t-anchor in a similar fashion which was in turnover-molded onto a silicone elastic tether 6 cm in length 1.5 mm indiameter attached to a silicone torpedo-shaped device body 2.5 cm inlength and 1 cm in diameter.

The devices were implanted using the implantation sequence described inFIGS. 23 a-c and Example 5 above. The three pigs were provided with 4days of recovery from the surgical intervention prior to entering asolid feed consumption trial. The pigs were provided commercial solidfeed in the form of pellets (Ambar, Israel), identical to the feedprovided commercially to pigs grown for meat production.

In all three pigs, no movement of the anchoring element or tissueerosion was detected, the devices remained in their original anchoringposition showing that through tissue anchoring using a t-bar anchoringelement and anti-erosion washer can be used to maintain a device withinthe stomach for extended time periods.

Example 7 Implantation of the Present Device in Pigs

Three female pigs (designated as 295 296 and 299), approximately 3months old, each weighing between 42-46 kg were selected for theimplantation of 2 different versions of the device of the presentinvention. Prior to device implantation, each pig was anesthetized.

Two anchoring configurations were deployed in this study, a barestainless steel t-bar anchor without a washer (endoscopically implantedin pig 295), and a t-bar anchor with a washer (silicone disc) interposedbetween the t-bar anchor and the sub-mucosal layer of the stomach(implanted in pigs 296 and 299). The washer functions in reducingpotential erosion and burrowing of the t-bar anchor through the mucosal,submucosal and muscle layers.

The t-bar anchors in both experiments were each attached to a Johnsonand Johnson Ethibond™ braided polyester suture (00) which was attachedto a 60 mm long silicone tether having a diameter of 1.5 mm. The devicebody attached to the tether was a 25 mm long silicone torpedo-shapedcylinder 10 mm in diameter.

The devices were maintained in the stomach of the pigs for 2 weeks,following which, each of the 3 pigs was anesthetized, and a diagnosticendoscopy was performed. Following imaging, the pigs were sacrificed,and their stomachs were harvested for histological examination.

Results

During the 2 week study, there were no problems or adverse eventsassociated with the 3 pigs in the study. FIG. 26 illustrates the anchorand attached device in Pig #295 (t-bar anchor without a washer). Allthree devices remained anchored and no signs of erosion or inflammationwere evident at the site of implantation throughout the 2 week study.

Device anchoring was also examined in the harvested stomachs of thesacrificed animals. The devices anchored using both of the abovedescribed approaches remained in place with no sign of erosion orinflammation at the anchoring sites. FIG. 27 illustrates harvestedstomach tissue with an attached device anchored via a t-bar anchor and asilicone washer (anchored in a live pig using the technique of Example 5and FIGS. 23 a-c). The sub-mucosal tissue around the anchoring siteappears normal and free of any signs of erosion or inflammation.

The harvested stomach tissue was sectioned around the site of anchorimplantation to reveal that anchoring depth ranged between 3.5-5 mm,demonstrating that the anchoring approach of the present inventionenables in-muscle anchoring without perforation of the serosa (i.e.extrusion of the anchor through the wall of the stomach). If desired, adeeper cup can be used to suction a larger fold of the tissue in orderto enable passing of the tether outside of the serosa and back into thestomach lumen.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents and patentapplications mentioned in this specification are herein incorporated intheir entirety by reference into the specification, to the same extentas if each individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

1-34. (canceled)
 35. A device for modifying an eating behavior of asubject comprising a device body attachable to tissue of a stomach, saiddevice body being sized and configured for passing through a pyloricopening when detached from said tissue of said stomach.
 36. The deviceof claim 35, wherein said device body is attached to said stomach tissuevia a tether.
 37. The device of claim 36, wherein a first end of saidtether is designed for anchoring in or through said tissue of saidstomach.
 38. The device of claim 35, wherein at least a portion of thedevice body is hollow.
 39. The device of claim 35 wherein said devicebody has a volume of 4 cm³ or less.
 40. The device of claim 35 whereinsaid device body has a surface area 15 cm² or less.
 41. The device ofclaim 36, wherein at least a portion of said tether can reversiblyincrease in length by least 25%.
 42. The device of claim 36, wherein atleast a portion of said device body is capable of moving between astomach and a duodenum when attached to said tissue of said stomach. 43.The device of claim 35, wherein said device body has a maximum diameterof 2 cm.
 44. The device of claim 36, wherein said tether is 0.5-10 cm inlength.
 45. The device of claim 35, wherein said device body includesone or more discs.
 46. The device of claim 35, wherein the device isconfigured for at least partially blocking said pylorus from the stomachor duodenal side.
 47. The device of claim 35, wherein said device bodyis capable of moving between an antrum and a duodenum with naturalperistaltic and reflux forces.
 48. The device of claim 35, wherein saiddevice body consists of one or more polymers.
 49. The device of claim35, wherein said device body is non-expandable.
 50. A method of alteringeating behavior in a subject comprising attaching a device to a tissueof a stomach of a subject in need, said device having a device bodybeing designed and configured for passing through a pylorus.
 51. Themethod of claim 50 wherein said device is attached to said stomachtissue via a tether.
 52. The method of claim 50 wherein said deviceintermittently and/or partially blocks the pylorus.
 53. A method ofanchoring a device in the stomach of a subject comprising passing afirst end of a tether through a stomach tissue fold wherein a second endof said tether is attached to a device body.
 54. The method of claim 53,wherein said first end of said tether passes through a washer.